VB Exercises: Basic Part

Slides

Slides for Basic VB Exercises

Slides for basic exercises can be downloaded here.

The Understanding of H2

Introduction

As a multiconfigurational quantum chemical method, a VBSCF calculation starts with the definition of the configuration space, i.e. active space (m,n), in which m active electrons arbitrarily distribute on n active orbitals. One can write totally three VB structures for hydrogen molecule by considering all singlet spin coupling patterns in the (2,2) active space. The three VB structures, namely covalent structure \(\Phi^{cov}\), and two ionic structures \(\Phi_1^{ion}\)and \(\Phi_2^{ion}\), are written as

\[\Phi^{cov}=\frac{1}{\sqrt{2+2S_{ab}}}\left( \vert \phi_a\overline{\phi_b}\vert - \vert \overline{\phi_a}\phi_b \vert \right)\]
\[\Phi_1^{ion}=\vert \phi_a\overline{\phi_a}\vert\]
\[\Phi_2^{ion}=\vert \phi_b\overline{\phi_b}\vert\]

where \(\phi_a\) and \(\phi_b\) are respectively the atomic orbitals of hydrogens a and b, \(s_{ab}\) is the orbital overlap between \(\phi_a\) and \(\phi_b\), and the bar over an orbital means a β spin orbital. Since no covalent bond is formed in the two ionic structures, each of the ionic structure is described by \(2^0=1\) determinant. The covalent structure consists one covalent bond, and hence is comprised of \(2^1=2\) determinants, namely \(|\phi_a\overline{\phi}_b|\) and \(|\overline{\phi}_a\phi_b|\). Note that neither of the determinants \(|\phi_a\overline{\phi}_b|\) nor \(|\overline{\phi}_a\phi_b|\) is the eigenfunction of \(\hat{S}^2\), and thus should be combined to form a spin-adapted VB structure. The three VB structures and their four expanded determinants are illustrated in the following figure.

_images/h2_2.jpg

The three VB structures and their four expanded determinants of H2 The VBSCF wave function of H2 molecule can thus be written as

\[\Psi=C^{cov}\Phi^{cov}+C^{ion}(\Phi_1^{ion}+\Phi_2^{ion})\]

where the coefficients of the two ionic structures are the same according to the symmetry of the H2 molecule. With cc-pvTZ basis set, the Coulson-Chirgwin weights of the three VB structures \(\Phi^{cov}\), \(\Phi_1^{ion}\) and \(\Phi_2^{ion}\) at the equilibrium bond length (R=0.75 Å) are respectively 0.82, 0.09 and 0.09, which indicates that the covalent bonding dominants the H2 molecule, but the ionic character still play a nonnegligible role for the homopolar bond. As the H-H bond stretched, the weight of the covalent structure gradually increases while the weights of the ionic structures decrease. At the dissociation limit the H-H bonding is purely covalent, which corresponds to the two neutral hydrogen atoms after bond dissociation. The following figure plots the weights of the covalent and ionic structures along the dissociation of H2 molecule. We demonstrate again the VB theory is natural multi-determinantal, even when only one covalent structure is involved in the wave function for bond breaking. The multi-determinant feature enables VB theory to correctly treat bond breaking and strongly-correlated systems.

_images/h2_3.jpg

Computation of H2 at Stationary Point

This exercise will provide a first glance at VB computation. The users will learn the struct and syntax of XMVB input, how to build a simple input file, how to run the job and what we will get from the output.

The computation is proceeded at the equilibrium bond lenght of 0.75 Å, and the basis set is cc-pVDZ. For simplicity, H atoms are located in the Z axis.

Input File

Running an XMVB job requires an input file with extension name “xmi”, which is composed of several sections. The following is an simplest example xmi input file of VBSCF calculation of H2.

H2 VBSCF with 3 structures
$CTRL
STR=FULL NAO=2 NAE=2 IPRINT=3
BASIS=CC-PVDZ
$END
$ORB
5 5
1-5
6-10
$END
$GEO
H 0.0 0.0 0.0
H 0.0 0.0 0.75
$END

The keywords in XMVB are case insensitive. The first line is the title of the job, and followed by several sections starting with $CTRL (or $STR, $ORB, $GEO, etc.) and ending with $END. The order of the sections can be arbitrary. The keywords within each section are separated by blanks and are not limited to a single line.

In an xmi file, the $CTRL and $GEO sections, which correspond to global control and molecular geometry, must be provided by the user, and other sections might be default in some cases. In the $CTRL section, NAE and NAO are respectively the numbers of active electrons and active orbitals, and (2,2) active space is used in this case; STR=FULL means all the 3 VB structures in the (2,2) active space are included; BASIS=CC-PVDZ means the cc-pVDZ basis set is used. No VB method is specified in this inputfile, and the default VBSCF calculation will be performed.

The $ORB section defines the VB orbitals. The first line specifies the numbers of basis functions to expand each orbital, each number separated by blanks. In this case (“NAO=2”), 5 5 means the two orbitals are expanded with 5 and 5 basis functions. With cc-pVDZ basis set, the basis functions of the first H atom (shown in the first line in $GEO section) are labeled as 1-5, while those of the second H atom (the second line in $GEO section) are labeled as 6-10. Thus, the second line 1-5 in $orb section means the first orbital is expanded by the basis functions of the first H atom, while the third line 6-10 means the second orbital is expanded by the basis functions of the second H atom.

Output File

The main XMVB output file has an “xmo” extension. The output file starts with the XMVB banner, then followed by the description of VB structures used in calculation, nuclear repulsion energy, initial orbital guess, and a repetition of the input file. For a VBSCF calculation, the information of orbital optimization (the energy and gradients) at each iteration is printed. After the end of the SCF procedure, the VBSCF wave function is printed, including the Hamiltonian and overlap matrices, VB structure and determinant coefficients, weights of VB structures, and the optimized orbitals. Finally, the charge and spin population analysis, bond order and dipole moments are printed. Following is a detailed explain of H 2 (corresponding to the input file in the previous section).

In the (2,2) active space, totally 3 structures (4 determinents) are involved in the VBSCF wave function.

Number of   0th ion  structures  is:          1  from          1 to          1
Number of   0th ion determinants is:          2  from          1 to          2
Number of   1th ion  structures  is:          2  from          2 to          3
Number of   1th ion determinants is:          2  from          3 to          4
Total number of  structures  is:          3
Total number of determinants is:          4
                   .
                   .
                   .
Number of Structures:           3

The following structures are used in calculation:

      1 *****  1   2
      2 *****  1   1
      3 *****  2   2

The user may find from the output file that the VBSCF converged after 6 iterations and the final energy is -1.14694448 hartree.

                       VBSCF converged in    6 iterations

Total Energy:    -1.14694448

First Excited:   -0.268326

The coefficients and weights shows the importance of each structure. Following are the coefficients and weights of generated VB structures. Both coefficients and weights show that the covalent structure is the dominant one. So the H-H bond should be a covalent bond.

       ******  COEFFICIENTS OF STRUCTURES ******

1    -0.83526891  ******  1   2
2    -0.09985465  ******  1   1
3    -0.09985465  ******  2   2
                  .
                  .
                  .
       ******  WEIGHTS OF STRUCTURES ******

1     0.83388006  ******  1   2
2     0.08305997  ******  1   1
3     0.08305997  ******  2   2

Finally, the bond order value (0.950) in atomic population analysis shows that H-H bond should be a single bond.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 H           2 H            0.750       0.950

Computing of F2

Introduction

F2 is a typical diatimic molecule which is simple enough for the users as a starting point. There is only 1 chemical bonding in the molecule. The 3 structures of the bonding is shown below.

_images/f2.jpg

Structures of F2 molecule

Here S1 denotes the covalent structure in which two active electrons are shared between both F atoms while S2 and S3 denote 2 quivalent ionic structures in which two active eletrons doubly occupy orbital on certain F atom.

In this exercise, we will try to proceed computations for the bond dissociation energy (BDE) and resnance energy (RE) of F2. This takes computations at stationary point and dissociation limit with various sets of VB structures.

In this example, we will also investigate the nature of the F-F bonding, which is not the conventional covalent or ionic bond, but is charge-shift bond.

Electron-pair bonding is a central chemical paradigm to describe and interpret the interaction between atoms in a molecule. The concepts of covalent and ionic bonds can be dated back to the ingenious hypothesis of Lewis in 1916, and are still widely accepted and used nowadays. The covalent bonding comes from the electron spin-pairing of adjacent atoms and thus strongly stabilizes the molecule, while the ionic bonding comes from the electrostatic interaction of two fragments with opposite charges. Typical covalent bonds are usually found between H, B, C, N, O atoms, while typical ionic bonds are formed with one alkali or alkaline earth metal atom and one halogen atom. However, despite great successes of traditional electron-pair bonding in explaining molecular stability and chemical reaction mechanisms, the chemical bonding even in some simple molecules, F2 for instance, cannot be unambiguously classified into covalent or ionic.

The following figure shows the dissociation curves of the total wave function and covalent structure for H2 and F2 molecules. For H2, the potential energy curve (PEC) of covalent structure is a little higher than that of the total wave function, but the topology of the both PECs is quite close. One thus concludes that the bonding in H2 is dominated by the covalent interaction between the two H atoms. For F2, however, the PEC of covalent structure is repulsive, and much higher than that of the total wave function, and the topology of the two PECs is totally different, i.e. the two F atoms tend to dissociate due to the covalent interaction. Since both the covalent and ionic interactions are non-bonding in F2, the bond dissociation energy (BDE) of F2, which is around 38.2 kcal/mol, is totally due to the resonance of the VB structures. Based on the above-mentioned novel bonding, Shaik and Hiberty et al. proposed a new type of chemical bond, charge-shift (CS) bond, in which the RE contributes over 50% to the BDE.

_images/f2_2.jpg

The dissociation curves of the total wave function and covalent structure for (a) H2 and (b) F2 molecules.

Note

This exercise just shows the users how to proceed a VBSCF computation for a specific molecule, what we can get from the output and how to analyze the results. The accurate computation of BDE of F2 requires higher level computational methods with delocalized inactive \(\pi\) orbitals.

Computations with 3 Structures at Stationary Point

The computations are proceeded with F-F bond length 1.4 Angstrom, and the basis set is cc-pVDZ. For simplicity, F atoms are located in the Z axis.

Input File

Here shows the XMVB input file for all 3 structures at stationary point:

F2 VBSCF with 3 structures
$CTRL
STR=FULL NAO=2 NAE=2 IPRINT=3
ORBTYP=HAO FRGTYP=SAO
BASIS=CC-PVDZ
$END
$FRAG
1*6
SPZDXXDYYDZZ 1
SPZDXXDYYDZZ 2
PXDXZ 1
PXDXZ 2
PYDYZ 1
PYDYZ 2
$END
$ORB
1*10
1
2
1
2
3
4
5
6
1
2
$END
$GEO
F 0.0 0.0 0.0
F 0.0 0.0 1.4
$END

The global keywords listed in $CTRL section are explained below:

  • STR=FULL XMVB generates all VB structures automatically according to a specific active space.

  • IPRINT=3 XMVB will print most information.

  • NAO=2 and NAE=2 Specify the active space with 2 active orbital and 2 active electrons respectively.

  • ORBTYP=HAO and FRGTYP=SAO The VB orbitals are described with fragments.

  • BASIS=CC-PVDZ The basis set is cc-pVDZ.

Note

The orbitals of a molecule can be devided into “inactive” and “active” parts. The inactive orbitals are always doubly occupied in all VB structures, while the occupation numbers of active orbitals can be 0, 1 or 2 in each VB structure.

$FRAG section describes the fragments used to construct VB orbitals. In this case, the first line 1*6 means that there are 6 fragments built and each fragment include only 1 atom. The details of fragments are described in the following lines. For example, SPZDXXDYYDZZ 1 means that the fragment includes s, pz, dxx, dyy and dzz basis functions on atom 1, which is the first F atom in this case.

$ORB section describes VB orbitals. The first line 1*10 means that there are 10 orbitals in this case, each consisting of only 1 fragment. Each line below describes one orbital. For example, the first orbital includes only fragment 1, meaning that this orbital locates on the first F atom and belongs to the \(\sigma\) space since the F-F lies on Z axis. Also, orbital 6 with fragment 4 shows that the orbital describes the \(\pi_x\) orbital on the first F atom.

$GEO section shows the geometry of F2 molecule. Both Cartesian and internal coordinates are supported.

Note

Since NAO=2 is specified in $CTRL section, the last 2 orbitals in $ORB should be the active orbitals.

It is highly recommended that active orbitals are always palced after the inactive ones. This may make the input file more readable and less possible to get error.

Computational Results

In this case, 3 VB structures are generated with 1 covalent structure (0th ion structure) and 2 ionic structures (1th ion structures). These structures can be expaned into 4 determinants.

Number of   0th ion  structures  is:          1  from          1 to          1
Number of   0th ion determinants is:          2  from          1 to          2
Number of   1th ion  structures  is:          2  from          2 to          3
Number of   1th ion determinants is:          2  from          3 to          4
Total number of  structures  is:          3
Total number of determinants is:          4
                   .
                   .
                   .
Number of Structures:           3

The following structures are used in calculation:

      1 *****  1:8    9  10
      2 *****  1:8    9   9
      3 *****  1:8   10  10

The user may find from the output file that the VBSCF converged after 25 iterations and the final energy is -198.75115493 hartree.

                       VBSCF converged in    25 iterations

Total Energy:    -198.75115493

First Excited:   -197.880879

The coefficients and weights shows the importance of each structure. Following are the coefficients and weights of generated VB structures. Both coefficients and weights show that the covalent structure is the dominant one. So the F-F bond should be a covalent bond.

       ******  COEFFICIENTS OF STRUCTURES ******

1    -0.80579  ******  1:8    9  10
2    -0.21326  ******  1:8    9   9
3    -0.21326  ******  1:8   10  10
                  .
                  .
                  .
       ******  WEIGHTS OF STRUCTURES ******

1     0.77586  ******  1:8    9  10
2     0.11207  ******  1:8    9   9
3     0.11207  ******  1:8   10  10

Finally, the bond order value (0.773) in atomic population analysis shows that F-F bond should be a single bond.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 F           2 F            1.400       0.773

Computations with 3 Structures at Dissociation Limit

Input File

The input file for such computation can be easily obtained by modifying the corresponding one at stationary point. As shown below, one just needs to modify the coordinate of the second F atom to change 1.4 to 10.0. This will increase the F-F bond distance to 10.0 Angstrom.

$GEO
F 0.0 0.0 0.0
F 0.0 0.0 10.0
$END

Computational Results

After SCF procedure, the user will get the final energy as shown below. The computational energy of dissociated F2 is -198.74386524 hartree.

Total Energy:    -198.74386524

First Excited:   -197.850852

Both coefficients and weights of VB structures show that the wave function includes only covalent structure, indicating that the molecule is dissociated to 2 F\(\cdot\) radicals.

       ******  COEFFICIENTS OF STRUCTURES ******

1     1.00000  ******  1:8    9  10
2     0.00000  ******  1:8    9   9
3     0.00000  ******  1:8   10  10
                      .
                      .
                      .
       ******  WEIGHTS OF STRUCTURES ******

1     1.00000  ******  1:8    9  10
2     0.00000  ******  1:8    9   9
3     0.00000  ******  1:8   10  10

By substracting energies at stationary point and dissociation limit, the BDE can be obtained as 4.4 kcal/mol.

Computations with Covalent Structure at Stationary Point

Input File

The input file can be obtained by replacing STR=FULL with STR=COV in the input file of 3 structures at stationary point, as shown below.

$CTRL
STR=COV NAO=2 NAE=2 IPRINT=3
ORBTYP=HAO FRGTYP=SAO
BASIS=CC-PVDZ
$END

Computational Results

The structure information is shown below. It can be seen that only 1 covalent structure is generated for this computation.

Number of   0th ion  structures  is:          1  from          1 to          1
Number of   0th ion determinants is:          2  from          1 to          2
Total number of  structures  is:          1
Total number of determinants is:          2
                       .
                       .
                       .
 Number of Structures:           1

 The following structures are used in calculation:

       1 *****  1:8    9  10

The final energy after SCF iteration is -198.67485969 hartree.

Total Energy:    -198.67485969

The Last Change in Energy:  -0.000000

The bond order result in atomic population analysis shows that the bond order with only covalent structure is 0.324, which is much smaller than computations with 3 structures.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 F           2 F            1.400       0.324

The RE value, 47.6 kcal/mol, can be obtained from energies by covalent and 3 structure computations at stationary point. Compared with the computational BDE 4.4, RE is much larger than BDE, indicating that the chemical bonding in F2 is an charge-shifting bond. The much smaller bond order data with only covalent structure also indicates that resonance plays an important role in the F-F bonding.

Resonance in C6H6

Introduction

Benzene (C6H6) is a classical aromatic molecule in which electrons in \(\pi\) space are delocalized. The covalent valence bond structures are shown in the following table.

_images/c6h6.png

Covalent Structures of C6H6

The 5 covalent structures can be classified as 2 types: the first 2 structures are Kekulé structures and the others are regarded as Dewar structures. In this exercise, the resonance energy in the benzene molecule will be computed to show how resonance stabilize the aromatic molecule.

Computations with 5 Covalent Structures

First, we will compute the energy with all 5 covalent structures.

Input File

The input file is shown below.

C6H6
$ctrl
str=cov nao=6 nae=6 iprint=3
orbtyp=hao frgtyp=sao
basis=cc-pvdz
$end
$frag
12 2*6
spxpydxxdyydzzdxy 1-12
pzdxzdyz 1 2
pzdxzdyz 3 4
pzdxzdyz 5 6
pzdxzdyz 7 8
pzdxzdyz 9 10
pzdxzdyz 11 12
$end
$orb
1*18 1*6
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
3
4
5
6
7
$end
$geo
 C           0.6995000584   1.2115696411   0.0000000000
 H           1.2460106991   2.1581538376   0.0000000000
 C          -0.6995000584   1.2115696411   0.0000000000
 H          -1.2460106991   2.1581538376   0.0000000000
 C          -1.3990001169   0.0000000000   0.0000000000
 H          -2.4920213982   0.0000000000   0.0000000000
 C          -0.6995000584  -1.2115696411   0.0000000000
 H          -1.2460106991  -2.1581538376   0.0000000000
 C           0.6995000584  -1.2115696411   0.0000000000
 H           1.2460106991  -2.1581538376   0.0000000000
 C           1.3990001169   0.0000000000   0.0000000000
 H           2.4920213982   0.0000000000   0.0000000000
$end

In this input file, the molecule lays in the XY plane. The fragments specified in $FRAG section are defined according to the symmetries. Since we concern on the resonance in \(\pi\)space, electrons locating in \(\sigma\)space is not in the interest. Thus eletrons in the \(\sigma\)orbitals can be treated as inactive ones and make them delocalized in all structures. To this reason, the first fragment is defined to include all basis functions in \(\sigma\) space in the molecule. The remained fragments denote \(\pi\) orbitals locates on each CH group.

Computational Results

5 VB structures will be generated in the computation and can be found in the output:

Number of Structures:           5

The following structures are used in calculation:

      1 *****  1:18  21  22  20  23  19  24
      2 *****  1:18  20  21  22  23  19  24
      3 *****  1:18  20  21  19  22  23  24
      4 *****  1:18  19  20  22  23  21  24
      5 *****  1:18  19  20  21  22  23  24

Final energy can be found after the VBSCF iteration as -230.63450 hartree.

Total Energy:    -230.63449533

Both coefficients and weights of VB structures show that structures are in 2 groups. Structure 2 and 5 correspond to the Kekulé structures, which are the dominant ones, and the others denote Dewar structures.

       ******  COEFFICIENTS OF STRUCTURES ******

1     0.14537  ******  1:18  21  22  20  23  19  24
2    -0.40098  ******  1:18  20  21  22  23  19  24
3     0.14537  ******  1:18  20  21  19  22  23  24
4     0.14537  ******  1:18  19  20  22  23  21  24
5    -0.40098  ******  1:18  19  20  21  22  23  24
       ******  WEIGHTS OF STRUCTURES ******

1     0.11245  ******  1:18  21  22  20  23  19  24
2     0.33132  ******  1:18  20  21  22  23  19  24
3     0.11245  ******  1:18  20  21  19  22  23  24
4     0.11245  ******  1:18  19  20  22  23  21  24
5     0.33132  ******  1:18  19  20  21  22  23  24

The atomic population analysis shows that the bond orders of all CC bondings are the same as 1.188, showing the effect of conjugation.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 C           2 H            1.093       0.979
 1 C           3 C            1.399       1.188
 3 C           4 H            1.093       0.979
 3 C           5 C            1.399       1.188
 5 C           6 H            1.093       0.979
 5 C           7 C            1.399       1.188
 7 C           8 H            1.093       0.979
 7 C           9 C            1.399       1.188
 9 C          10 H            1.093       0.979
 1 C          11 C            1.399       1.188
 9 C          11 C            1.399       1.188
11 C          12 H            1.093       0.979

Computations with 2 Kekulé Structures

Input File

The input file is shown below.

C6H6
$ctrl
nstr=2 nao=6 nae=6 iprint=3
orbtyp=hao frgtyp=sao
basis=cc-pvdz
guess=read
$end
$str
1:18 19-24
1:18 19 24 20 21 22 23
$end
$frag
12 2*6
spxpydxxdyydzzdxy 1-12
pzdxzdyz 1 2
pzdxzdyz 3 4
pzdxzdyz 5 6
pzdxzdyz 7 8
pzdxzdyz 9 10
pzdxzdyz 11 12
$end
$orb
1*18 1*6
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
3
4
5
6
7
$end
$geo
 C           0.6995000584   1.2115696411   0.0000000000
 H           1.2460106991   2.1581538376   0.0000000000
 C          -0.6995000584   1.2115696411   0.0000000000
 H          -1.2460106991   2.1581538376   0.0000000000
 C          -1.3990001169   0.0000000000   0.0000000000
 H          -2.4920213982   0.0000000000   0.0000000000
 C          -0.6995000584  -1.2115696411   0.0000000000
 H          -1.2460106991  -2.1581538376   0.0000000000
 C           0.6995000584  -1.2115696411   0.0000000000
 H           1.2460106991  -2.1581538376   0.0000000000
 C           1.3990001169   0.0000000000   0.0000000000
 H           2.4920213982   0.0000000000   0.0000000000
$end
$gus
    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90     5     5     5     5     5     5
# ORBITAL          1  NAO =      90
-0.4085807072     1  -0.0018715270     2   0.0001649808     3   0.0000999746     4
 0.0001985368     5   0.0000470242     7   0.0000880828     8   0.0009574571    10
 0.0000833088    11   0.0010378240    13   0.0011389938    15  -0.0001957425    16
-0.0001334195    17   0.0000477351    18   0.0000812855    19  -0.4085807076    21
-0.0018715190    22   0.0001649828    23  -0.0000999676    24   0.0001985300    25
-0.0000470232    27   0.0000880811    28   0.0009574481    30  -0.0000833266    31
 0.0010378340    33   0.0011390026    35  -0.0001957414    36  -0.0001334204    37
-0.0000477371    38   0.0000812776    39  -0.4090845359    41  -0.0018966521    42
 0.0001488619    43  -0.0002148556    44   0.0000001381    45  -0.0000988751    47
 0.0000000169    48   0.0010810968    50  -0.0000001656    51   0.0009153322    53
 0.0011399821    55  -0.0002143575    56  -0.0001372115    57  -0.0000966788    58
 0.0000001529    59  -0.4085807085    61  -0.0018714717    62   0.0001649779    63
-0.0001000242    64  -0.0001983775    65  -0.0000470512    67  -0.0000879863    68
 0.0009574723    70   0.0000839012    71   0.0010378364    73   0.0011390336    75
-0.0001956328    76  -0.0001334448    77  -0.0000479296    78  -0.0000811013    79
-0.4085807082    81  -0.0018714747    82   0.0001649755    83   0.0001000278    84
-0.0001983820    85   0.0000470479    87  -0.0000879885    88   0.0009574749    90
-0.0000838796    91   0.0010378346    93   0.0011390280    95  -0.0001956337    96
-0.0001334457    97   0.0000479178    98  -0.0000811144    99  -0.4090845352   101
-0.0018966413   102   0.0001488609   103   0.0002148576   104   0.0000001396   105
 0.0000988788   107   0.0000000209   108   0.0010810705   110   0.0000001777   111
 0.0009153543   113   0.0011399863   115  -0.0002143672   116  -0.0001372134   117
 0.0000966809   118   0.0000001629   119
# ORBITAL          2  NAO =      90
 0.2888930861     1   0.0012304770     2  -0.0002563966     3   0.0001336859     4
-0.0001561191     5   0.0001914831     7  -0.0001481897     8  -0.0008221343    10
-0.0001557600    11  -0.0005906595    13  -0.0007980351    15   0.0001543642    16
 0.0000791296    17   0.0000125324    18  -0.0000788689    19  -0.2888931497    21
-0.0012304753    22   0.0002562013    23   0.0001337942    24   0.0001566737    25
 0.0001915140    27   0.0001494777    28   0.0008219804    30  -0.0001516843    31
 0.0005907316    33   0.0007979421    35  -0.0001550608    36  -0.0000790540    37
 0.0000136909    38   0.0000800072    39  -0.5781904466    41  -0.0024581181    42
 0.0005050109    43  -0.0001390292    44   0.0000000205    45  -0.0000746810    47
 0.0000000140    48   0.0015287631    50  -0.0000000553    51   0.0012982685    53
 0.0015971801    55  -0.0003048222    56  -0.0001585226    57  -0.0001238936    58
 0.0000000479    59  -0.2888930865    61  -0.0012304541    62   0.0002561993    63
 0.0001337970    64  -0.0001566499    65   0.0001915245    67  -0.0001494674    68
 0.0008219645    70   0.0001517465    71   0.0005907569    73   0.0007979557    75
-0.0001550484    76  -0.0000790645    77   0.0000136980    78  -0.0000799949    79
 0.2888931500    81   0.0012304673    82  -0.0002563957    83   0.0001337007    84
 0.0001561303    85   0.0001914997    87   0.0001482011    88  -0.0008221145    90
 0.0001556889    91  -0.0005906834    93  -0.0007980414    95   0.0001543768    96
 0.0000791346    97   0.0000125801    98   0.0000788956    99   0.5781904449   101
 0.0024591332   102  -0.0005052562   103  -0.0001393968   104   0.0000000109   105
-0.0000739491   107  -0.0000000104   108  -0.0015297884   110  -0.0000000183   111
-0.0012968826   113  -0.0015966043   115   0.0003041670   116   0.0001581403   117
-0.0001241023   118  -0.0000000148   119
# ORBITAL          3  NAO =      90
 0.5006118878     1   0.0021171792     2  -0.0004445363     3  -0.0001718795     4
-0.0000528411     5  -0.0001543791     7   0.0000142568     8  -0.0010905424    10
-0.0000444470    11  -0.0013582539    13  -0.0013824483    15   0.0002505625    16
 0.0001341232    17  -0.0000778672    18  -0.0000745639    19   0.5006118515    21
 0.0021171388    22  -0.0004445339    23   0.0001718621    24  -0.0000528197    25
 0.0001543481    27   0.0000142554    28  -0.0010905019    30   0.0000444391    31
-0.0013583104    33  -0.0013824752    35   0.0002505629    36   0.0001341408    37
 0.0000778110    38  -0.0000745770    39  -0.0000000362    41   0.0000000221    42
-0.0000000048    43   0.0000000087    44   0.0002083308    45  -0.0000000157    47
 0.0002704667    48  -0.0000000212    50   0.0002206198    51   0.0000000294    53
 0.0000000132    55  -0.0000000141    56  -0.0000000081    57   0.0000000045    58
 0.0000602462    59  -0.5006118875    61  -0.0021171392    62   0.0004445257    63
-0.0001718574    64  -0.0000528443    65  -0.0001543471    67   0.0000142010    68
 0.0010904959    70   0.0000442655    71   0.0013583140    73   0.0013824713    75
-0.0002505931    76  -0.0001341382    77  -0.0000777637    78  -0.0000746227    79
-0.5006118506    81  -0.0021171793    82   0.0004445278    83   0.0001718746    84
-0.0000528666    85   0.0001543776    87   0.0000142018    88   0.0010905358    90
-0.0000442668    91   0.0013582572    93   0.0013824439    95  -0.0002505929    96
-0.0001341203    97   0.0000778157    98  -0.0000746149    99   0.0000000372   101
 0.0000000233   102  -0.0000000051   103  -0.0000000081   104   0.0002082947   105
 0.0000000157   107   0.0002704090   108  -0.0000000235   110  -0.0002208132   111
 0.0000000315   113   0.0000000132   115  -0.0000000150   116  -0.0000000085   117
-0.0000000048   118   0.0000600832   119
# ORBITAL          4  NAO =      90
-0.2891567875     1  -0.0011788380     2   0.0006696401     3   0.0001162136     4
-0.0000434029     5   0.0000569096     7  -0.0002181218     8   0.0005581052    10
-0.0000173221    11   0.0007001594    13   0.0007639834    15  -0.0000761592    16
-0.0000306619    17   0.0000222375    18   0.0000003327    19  -0.2891568478    21
-0.0011788552    22   0.0006696375    23  -0.0001162265    24  -0.0000433901    25
-0.0000569145    27  -0.0002181183    28   0.0005581234    30   0.0000173582    31
 0.0007001375    33   0.0007639670    35  -0.0000761610    36  -0.0000306572    37
-0.0000222376    38   0.0000003522    39   0.5781677329    41   0.0024208733    42
-0.0012969300    43  -0.0000049661    44  -0.0000000187    45  -0.0003380963    47
 0.0000000028    48  -0.0013034129    50   0.0000000076    51  -0.0012070190    53
-0.0015287103    55   0.0002187599    56   0.0000735925    57   0.0000329236    58
-0.0000000083    59  -0.2891567879    61  -0.0011788549    62   0.0006696380    63
-0.0001162154    64   0.0000433692    65  -0.0000569033    67   0.0002181026    68
 0.0005581117    70  -0.0000174532    71   0.0007001480    73   0.0007639674    75
-0.0000761793    76  -0.0000306569    77  -0.0000221958    78  -0.0000003814    79
-0.2891568468    81  -0.0011788535    82   0.0006696419    83   0.0001162088    84
 0.0000433741    85   0.0000569103    87   0.0002181062    88   0.0005581088    90
 0.0000174178    91   0.0007001487    93   0.0007639740    95  -0.0000761773    96
-0.0000306542    97   0.0000222162    98  -0.0000003606    99   0.5781677327   101
 0.0024208558   102  -0.0012969285   103   0.0000049612   104  -0.0000000253   105
 0.0003380902   107  -0.0000000083   108  -0.0013033682   110  -0.0000000436   111
-0.0012070582   113  -0.0015287170   115   0.0002187773   116   0.0000735959   117
-0.0000329255   118  -0.0000000388   119
# ORBITAL          5  NAO =      90
-0.5007497195     1  -0.0020926701     2   0.0011274729     3  -0.0000664898     4
 0.0000686296     5  -0.0002263515     7  -0.0001918806     8   0.0011015128    10
 0.0000674501    11   0.0010736729    13   0.0013237329    15  -0.0001590050    16
-0.0000498765    17   0.0000054571    18   0.0000298585    19   0.5007496847    21
 0.0020926790    22  -0.0011275085    23  -0.0000664796    24  -0.0000685616    25
-0.0002263533    27   0.0001920864    28  -0.0011015340    30   0.0000680448    31
-0.0010736610    33  -0.0013237436    35   0.0001589047    36   0.0000498846    37
 0.0000056242    38  -0.0000296943    39   0.0000000348    41   0.0000000890    42
-0.0000000212    43   0.0000000320    44   0.0001851945    45  -0.0000000646    47
 0.0002002088    48  -0.0000000915    50   0.0000942443    51   0.0000001220    53
 0.0000000504    55  -0.0000000578    56  -0.0000000328    57   0.0000000176    58
 0.0000247770    59  -0.5007497199    61  -0.0020926786    62   0.0011274738    63
 0.0000664970    64  -0.0000686556    65   0.0002263560    67   0.0001918646    68
 0.0011015108    70   0.0000673487    71   0.0010736709    73   0.0013237272    75
-0.0001590238    76  -0.0000498723    77  -0.0000054290    78  -0.0000298875    79
 0.5007496855    81   0.0020926723    82  -0.0011275078    83   0.0000664707    84
 0.0000685365    85   0.0002263476    87  -0.0001921026    88  -0.0011015386    90
 0.0000681438    91  -0.0010736605    93  -0.0013237484    95   0.0001588863    96
 0.0000498882    97  -0.0000056552    98   0.0000296659    99   0.0000000336   101
 0.0000000883   102  -0.0000000217   103  -0.0000000323   104  -0.0001852396   105
 0.0000000644   107  -0.0002002133   108  -0.0000000900   110   0.0000941944   111
 0.0000001203   113   0.0000000496   115  -0.0000000565   116  -0.0000000328   117
-0.0000000169   118  -0.0000248210   119
# ORBITAL          6  NAO =      90
 0.4091251475     1   0.0018241997     2  -0.0036592202     3   0.0000020694     4
-0.0000011859     5   0.0007741716     7   0.0013387077     8  -0.0007515405    10
 0.0000812994    11  -0.0006732113    13  -0.0009930082    15  -0.0000359553    16
-0.0002099914    17   0.0000257544    18   0.0000416529    19  -0.4091251464    21
-0.0018242229    22   0.0036594107    23   0.0000019865    24   0.0000007218    25
 0.0007741606    27  -0.0013398977    28   0.0007516717    30   0.0000776616    31
 0.0006731473    33   0.0009930840    35   0.0000365738    36   0.0002099303    37
 0.0000247332    38  -0.0000426613    39   0.4088400900    41   0.0018185067    42
-0.0036610579    43  -0.0000000395    44   0.0000000662    45  -0.0015467853    47
 0.0000000329    48  -0.0006312514    50  -0.0000001499    51  -0.0007924283    53
-0.0009926163    55  -0.0000380211    56  -0.0002097659    57  -0.0000506940    58
 0.0000001297    59  -0.4091251455    61  -0.0018241642    62   0.0036594070    63
 0.0000019879    64  -0.0000006481    65   0.0007741792    67   0.0013399307    68
 0.0007516425    70  -0.0000774650    71   0.0006732027    73   0.0009931240    75
 0.0000366093    76   0.0002099034    77   0.0000247197    78   0.0000427155    79
 0.4091251465    81   0.0018241721    82  -0.0036592195    83   0.0000021021    84
 0.0000012118    85   0.0007742169    87  -0.0013386734    88  -0.0007514874    90
-0.0000814990    91  -0.0006732734    93  -0.0009930272    95  -0.0000359181    96
-0.0002099801    97   0.0000258758    98  -0.0000415851    99  -0.4088400890   101
-0.0018194794   102   0.0036612935   103   0.0000003129   104   0.0000000252   105
-0.0015474894   107  -0.0000000271   108   0.0006322381   110  -0.0000000559   111
 0.0007910987   113   0.0009920653   115   0.0000386489   116   0.0002101309   117
-0.0000504971   118  -0.0000000437   119
# ORBITAL          7  NAO =      90
-0.0107819418     1   0.1790782666     2   0.0924284475     3  -0.0318865151     4
-0.0553049355     5  -0.0062977525     7  -0.0109401070     8   0.0108331095    10
-0.0038054399    11   0.0070287849    13  -0.0063313721    15   0.0455977157    16
 0.0036387887    17  -0.0036035054    18  -0.0062459698    19  -0.0107819418    21
 0.1790782665    22   0.0924284475    23   0.0318865153    24  -0.0553049354    25
 0.0062977526    27  -0.0109401069    28   0.0108331095    30   0.0038054400    31
 0.0070287847    33  -0.0063313720    35   0.0455977157    36   0.0036387887    37
 0.0036035054    38  -0.0062459697    39  -0.0107755990    41   0.1791237848    42
 0.0924406313    43   0.0638465961    44  -0.0000000002    45   0.0126243430    47
 0.0000000000    48   0.0051202404    50   0.0000000002    51   0.0127397005    53
-0.0063317099    55   0.0456056414    56   0.0036342774    57   0.0072116661    58
-0.0000000001    59  -0.0107819418    61   0.1790782665    62   0.0924284475    63
 0.0318865153    64   0.0553049352    65   0.0062977526    67   0.0109401069    68
 0.0108331095    70  -0.0038054405    71   0.0070287846    73  -0.0063313721    75
 0.0455977156    76   0.0036387886    77   0.0036035055    78   0.0062459696    79
-0.0107819418    81   0.1790782665    82   0.0924284475    83  -0.0318865153    84
 0.0553049354    85  -0.0062977525    87   0.0109401069    88   0.0108331095    90
 0.0038054404    91   0.0070287849    93  -0.0063313722    95   0.0455977156    96
 0.0036387887    97  -0.0036035055    98   0.0062459696    99  -0.0107755990   101
 0.1791237842   102   0.0924406314   103  -0.0638465970   104  -0.0000000002   105
-0.0126243426   107   0.0000000000   108   0.0051202413   110  -0.0000000001   111
 0.0127397007   113  -0.0063317099   115   0.0456056422   116   0.0036342781   117
-0.0072116650   118  -0.0000000001   119
# ORBITAL          8  NAO =      90
 0.0080809826     1  -0.1247496483     2  -0.0702559576     3  -0.0784948406     4
 0.0639689094     5  -0.0281707685     7   0.0270146479     8   0.0056247890    10
 0.0119191820    11  -0.0144007347    13   0.0039111625    15  -0.0517266720    16
-0.0069585491    17   0.0014215117    18   0.0074905042    19  -0.0080809832    21
 0.1247496564    22   0.0702559624    23  -0.0784948380    24  -0.0639689094    25
-0.0281707673    27  -0.0270146491    28  -0.0056247882    30   0.0119191787    31
 0.0144007344    33  -0.0039111628    35   0.0517266760    36   0.0069585494    37
 0.0014215110    38  -0.0074905056    39  -0.0161618860    41   0.2495029330    42
 0.1404967375    43   0.0323045190    44   0.0000000022    45   0.0186150565    47
 0.0000000009    48   0.0009097151    50   0.0000000004    51   0.0166398753    53
-0.0078227360    55   0.1034460314    56   0.0139150017    57   0.0143938231    58
 0.0000000000    59  -0.0080809826    61   0.1247496481    62   0.0702559577    63
-0.0784948405    64   0.0639689095    65  -0.0281707683    67   0.0270146490    68
-0.0056247889    70  -0.0119191785    71   0.0144007345    73  -0.0039111625    75
 0.0517266726    76   0.0069585489    77   0.0014215107    78   0.0074905052    79
 0.0080809832    81  -0.1247496565    82  -0.0702559623    83  -0.0784948381    84
-0.0639689091    85  -0.0281707675    87  -0.0270146480    88   0.0056247883    90
-0.0119191823    91  -0.0144007346    93   0.0039111629    95  -0.0517266754    96
-0.0069585496    97   0.0014215120    98  -0.0074905046    99   0.0161618860   101
-0.2495029327   102  -0.1404967374   103   0.0323045205   104   0.0000000024   105
 0.0186150551   107   0.0000000008   108  -0.0009097149   110  -0.0000000002   111
-0.0166398772   113   0.0078227354   115  -0.1034460320   116  -0.0139150025   117
 0.0143938213   118   0.0000000001   119
# ORBITAL          9  NAO =      90
 0.0139974362     1  -0.2160783634     2  -0.1216786927     3   0.0639676065     4
-0.0045967336     5   0.0270145605     7   0.0030327889     8  -0.0179215924    10
 0.0022068301    11   0.0027201810    13   0.0067737890    15  -0.0895686954    16
-0.0120431588    17   0.0074907427    18   0.0100672464    19   0.0139974359    21
-0.2160783579    22  -0.1216786897    23  -0.0639676097    24  -0.0045967367    25
-0.0270145618    27   0.0030327877    28  -0.0179215926    30  -0.0022068299    31
 0.0027201819    33   0.0067737894    35  -0.0895686936    36  -0.0120431585    37
-0.0074907427    38   0.0100672457    39  -0.0000000003    41   0.0000000048    42
 0.0000000027    43   0.0000000006    44  -0.1154605477    45   0.0000000003    47
-0.0437801763    48   0.0000000000    50  -0.0184419859    51   0.0000000003    53
-0.0000000002    55   0.0000000020    56   0.0000000003    57   0.0000000003    58
-0.0029035178    59  -0.0139974362    61   0.2160783627    62   0.1216786924    63
 0.0639676067    64  -0.0045967344    65   0.0270145607    67   0.0030327888    68
 0.0179215924    70  -0.0022068304    71  -0.0027201814    73  -0.0067737896    75
 0.0895686955    76   0.0120431587    77   0.0074907427    78   0.0100672461    79
-0.0139974359    81   0.2160783587    82   0.1216786899    83  -0.0639676095    84
-0.0045967361    85  -0.0270145616    87   0.0030327879    88   0.0179215927    90
 0.0022068297    91  -0.0027201816    93  -0.0067737889    95   0.0895686934    96
 0.0120431584    97  -0.0074907426    98   0.0100672461    99   0.0000000003   101
-0.0000000048   102  -0.0000000027   103   0.0000000006   104  -0.1154605457   105
 0.0000000004   107  -0.0437801767   108  -0.0000000001   110   0.0184419877   111
-0.0000000003   113   0.0000000001   115  -0.0000000020   116  -0.0000000003   117
 0.0000000003   118  -0.0029035175   119
# ORBITAL         10  NAO =      90
-0.0051440589     1   0.1005718952     2   0.0845638529     3  -0.1397337895     4
 0.1141834782     5  -0.0457303867     7   0.0234939964     8   0.0117656669    10
 0.0056709072    11  -0.0100493795    13  -0.0019026433    15   0.0770087430    16
 0.0164532289    17  -0.0072726819    18  -0.0060307741    19  -0.0051440587    21
 0.1005718915    22   0.0845638499    23   0.1397337914    24   0.1141834780    25
 0.0457303869    27   0.0234939969    28   0.0117656673    30  -0.0056709071    31
-0.0100493799    33  -0.0019026433    35   0.0770087402    36   0.0164532285    37
 0.0072726816    38  -0.0060307738    39   0.0102806964    41  -0.2012853772    42
-0.1692333678    43   0.0582639973    44  -0.0000000022    45  -0.0049551221    47
-0.0000000006    48   0.0006914310    50  -0.0000000001    51  -0.0041279010    53
 0.0038040175    55  -0.1542612985    56  -0.0329629875    57  -0.0177440549    58
-0.0000000001    59  -0.0051440589    61   0.1005718952    62   0.0845638530    63
 0.1397337890    64  -0.1141834780    65   0.0457303863    67  -0.0234939964    68
 0.0117656672    70   0.0056709069    71  -0.0100493798    73  -0.0019026434    75
 0.0770087429    76   0.0164532290    77   0.0072726817    78   0.0060307742    79
-0.0051440587    81   0.1005718916    82   0.0845638498    83  -0.1397337917    84
-0.1141834783    85  -0.0457303871    87  -0.0234939968    88   0.0117656669    90
-0.0056709073    91  -0.0100493797    93  -0.0019026432    95   0.0770087402    96
 0.0164532283    97  -0.0072726818    98   0.0060307738    99   0.0102806964   101
-0.2012853761   102  -0.1692333681   103  -0.0582639958   104   0.0000000022   105
 0.0049551210   107   0.0000000006   108   0.0006914310   110  -0.0000000001   111
-0.0041279019   113   0.0038040170   115  -0.1542612996   116  -0.0329629888   117
 0.0177440529   118   0.0000000001   119
# ORBITAL         11  NAO =      90
-0.0088998256     1   0.1742799331     2   0.1465089246     3   0.1142486920     4
-0.0078131644     5   0.0235313039     7  -0.0185720459     8  -0.0034227095    10
-0.0060473270    11   0.0064037031    13  -0.0032944140    15   0.1334935781    16
 0.0285120656    17  -0.0060359574    18  -0.0142465448    19   0.0088998257    21
-0.1742799344    22  -0.1465089259    23   0.1142486881    24   0.0078131605    25
 0.0235313028    27   0.0185720448    28   0.0034227096    30  -0.0060473293    31
-0.0064037026    33   0.0032944147    35  -0.1334935795    36  -0.0285120659    37
-0.0060359581    38   0.0142465441    39  -0.0000000001    41   0.0000000021    42
 0.0000000018    43  -0.0000000007    44  -0.2057016988    45   0.0000000001    47
-0.0593097208    48  -0.0000000000    50  -0.0158714988    51   0.0000000000    53
-0.0000000001    55   0.0000000016    56   0.0000000003    57   0.0000000002    58
-0.0037832706    59  -0.0088998256    61   0.1742799323    62   0.1465089241    63
-0.1142486911    64   0.0078131629    65  -0.0235313036    67   0.0185720454    68
-0.0034227098    70  -0.0060473291    71   0.0064037028    73  -0.0032944147    75
 0.1334935779    76   0.0285120654    77   0.0060359579    78   0.0142465442    79
 0.0088998257    81  -0.1742799352    82  -0.1465089263    83  -0.1142486891    84
-0.0078131618    85  -0.0235313029    87  -0.0185720453    88   0.0034227093    90
-0.0060473274    91  -0.0064037028    93   0.0032944141    95  -0.1334935796    96
-0.0285120659    97   0.0060359576    98  -0.0142465449    99  -0.0000000001   101
 0.0000000020   102   0.0000000018   103   0.0000000006   104   0.2057016950   105
-0.0000000001   107   0.0593097217   108   0.0000000001   110  -0.0158715011   111
-0.0000000001   113  -0.0000000000   115   0.0000000017   116   0.0000000004   117
-0.0000000002   118   0.0037832703   119
# ORBITAL         12  NAO =      90
-0.0037231920     1   0.0111150627     2   0.0324659518     3   0.0947657341     4
 0.1639019892     5   0.0324226748     7   0.0560650241     8   0.0004508783    10
-0.0049970547    11  -0.0045275601    13   0.0010122333    15   0.1490787651    16
 0.0353865179    17  -0.0067083649    18  -0.0116265648    19  -0.0037231920    21
 0.0111150626    22   0.0324659517    23  -0.0947657340    24   0.1639019892    25
-0.0324226745    27   0.0560650241    28   0.0004508780    30   0.0049970544    31
-0.0045275597    33   0.0010122332    35   0.1490787652    36   0.0353865178    37
 0.0067083650    38  -0.0116265647    39  -0.0037179973    41   0.0112563382    42
 0.0325136599    43  -0.1892984480    44  -0.0000000001    45  -0.0647516749    47
-0.0000000000    48  -0.0070415813    50   0.0000000001    51   0.0029723742    53
 0.0010156547    55   0.1491231283    56   0.0353714222    57   0.0134368381    58
-0.0000000001    59  -0.0037231920    61   0.0111150627    62   0.0324659517    63
-0.0947657339    64  -0.1639019894    65  -0.0324226745    67  -0.0560650241    68
 0.0004508780    70  -0.0049970546    71  -0.0045275596    73   0.0010122332    75
 0.1490787651    76   0.0353865177    77   0.0067083651    78   0.0116265647    79
-0.0037231920    81   0.0111150627    82   0.0324659518    83   0.0947657342    84
-0.1639019894    85   0.0324226748    87  -0.0560650241    88   0.0004508784    90
 0.0049970549    91  -0.0045275602    93   0.0010122333    95   0.1490787649    96
 0.0353865178    97  -0.0067083650    98   0.0116265649    99  -0.0037179973   101
 0.0112563375   102   0.0325136602   103   0.1892984469   104  -0.0000000001   105
 0.0647516758   107  -0.0000000000   108  -0.0070415822   110  -0.0000000002   111
 0.0029723750   113   0.0010156554   115   0.1491231290   116   0.0353714232   117
-0.0134368367   118  -0.0000000001   119
# ORBITAL         13  NAO =      90
-0.0077795017     1   0.1114492677     2   0.1676977293     3   0.0636506129     4
 0.1102407267     5   0.0070910121     7   0.0122634165     8  -0.0147424044    10
 0.0206787210    11   0.0059331824    13   0.0000881382    15   0.1838685648    16
 0.0693750950    17  -0.0071295317    18  -0.0123503755    19   0.0077795017    21
-0.1114492677    22  -0.1676977292    23   0.0636506129    24  -0.1102407270    25
 0.0070910126    27  -0.0122634173    28   0.0147424042    30   0.0206787185    31
-0.0059331821    33  -0.0000881383    35  -0.1838685644    36  -0.0693750951    37
-0.0071295320    38   0.0123503750    39  -0.0077800331    41   0.1114379546    42
 0.1677056671    43  -0.1272989969    44   0.0000000000    45  -0.0141745507    47
-0.0000000000    48   0.0162731269    50   0.0000000000    51  -0.0250837618    53
 0.0000883276    55   0.1838681097    56   0.0693765065    57   0.0142627162    58
 0.0000000000    59   0.0077795017    61  -0.1114492678    62  -0.1676977292    63
 0.0636506129    64   0.1102407272    65   0.0070910126    67   0.0122634172    68
 0.0147424042    70  -0.0206787184    71  -0.0059331821    73  -0.0000881382    75
-0.1838685642    76  -0.0693750950    77  -0.0071295322    78  -0.0123503751    79
-0.0077795017    81   0.1114492677    82   0.1676977293    83   0.0636506130    84
-0.1102407268    85   0.0070910120    87  -0.0122634164    88  -0.0147424044    90
-0.0206787211    91   0.0059331824    93   0.0000881382    95   0.1838685647    96
 0.0693750949    97  -0.0071295317    98   0.0123503756    99   0.0077800331   101
-0.1114379543   102  -0.1677056673   103  -0.1272989948   104   0.0000000001   105
-0.0141745525   107   0.0000000000   108  -0.0162731262   110   0.0000000001   111
 0.0250837603   113  -0.0000883285   115  -0.1838681106   116  -0.0693765078   117
 0.0142627144   118   0.0000000001   119
# ORBITAL         14  NAO =      90
 0.0000011888     1  -0.0000428122     2  -0.0000193406     3  -0.2396559405     4
 0.1383212588     5  -0.0833040860     7   0.0480780537     8   0.0081916407    10
 0.0054632598    11  -0.0081940522    13   0.0000021430    15  -0.0000568495    16
-0.0000165189    17  -0.0045591993    18   0.0026388067    19   0.0000011888    21
-0.0000428110    22  -0.0000193401    23   0.2396559394    24   0.1383212571    25
 0.0833040855    27   0.0480780535    28   0.0081916411    30  -0.0054632601    31
-0.0081940519    33   0.0000021439    35  -0.0000568498    36  -0.0000165188    37
 0.0045591989    38   0.0026388061    39  -0.0000000000    41  -0.0000000000    42
-0.0000000000    43  -0.0000000000    44  -0.2767352102    45  -0.0000000000    47
-0.0961986294    48  -0.0000000001    50  -0.0109202542    51   0.0000000000    53
-0.0000000001    55  -0.0000000000    56  -0.0000000000    57  -0.0000000000    58
-0.0052745169    59  -0.0000011888    61   0.0000428110    62   0.0000193401    63
-0.2396559396    64   0.1383212572    65  -0.0833040854    67   0.0480780534    68
-0.0081916410    70  -0.0054632601    71   0.0081940518    73  -0.0000021439    75
 0.0000568498    76   0.0000165188    77  -0.0045591989    78   0.0026388060    79
-0.0000011888    81   0.0000428123    82   0.0000193406    83   0.2396559404    84
 0.1383212588    85   0.0833040860    87   0.0480780537    88  -0.0081916407    90
 0.0054632598    91   0.0081940523    93  -0.0000021429    95   0.0000568495    96
 0.0000165189    97   0.0045591993    98   0.0026388067    99  -0.0000000000   101
 0.0000000001   102  -0.0000000000   103  -0.0000000000   104  -0.2767352058   105
-0.0000000000   107  -0.0961986304   108  -0.0000000000   110   0.0109202573   111
 0.0000000000   113  -0.0000000001   115  -0.0000000000   116  -0.0000000000   117
 0.0000000000   118  -0.0052745165   119
# ORBITAL         15  NAO =      90
-0.0006266032     1  -0.0382787571     2  -0.0483997291     3   0.1633248653     4
 0.1961580581     5   0.0509526263     7   0.0877847417     8  -0.0121775015    10
 0.0001460825    11   0.0084420611    13   0.0009659969    15   0.1928592179    16
 0.0682975466    17  -0.0044975288    18  -0.0126684488    19  -0.0006266032    21
-0.0382787568    22  -0.0483997291    23  -0.1633248656    24   0.1961580581    25
-0.0509526265    27   0.0877847418    28  -0.0121775014    30  -0.0001460827    31
 0.0084420612    33   0.0009659972    35   0.1928592182    36   0.0682975468    37
 0.0044975286    38  -0.0126684491    39  -0.0000000000    41  -0.0000000001    42
-0.0000000001    43  -0.0000000005    44  -0.0865394535    45  -0.0000000003    47
-0.0003977750    48  -0.0000000001    50  -0.0204636857    51   0.0000000000    53
-0.0000000000    55   0.0000000003    56   0.0000000001    57   0.0000000000    58
-0.0048836154    59   0.0006266032    61   0.0382787567    62   0.0483997289    63
 0.1633248656    64   0.1961580577    65   0.0509526263    67   0.0877847414    68
 0.0121775015    70  -0.0001460828    71  -0.0084420614    73  -0.0009659972    75
-0.1928592177    76  -0.0682975466    77  -0.0044975287    78  -0.0126684492    79
 0.0006266032    81   0.0382787572    82   0.0483997292    83  -0.1633248655    84
 0.1961580588    85  -0.0509526262    87   0.0877847417    88   0.0121775015    90
 0.0001460827    91  -0.0084420611    93  -0.0009659969    95  -0.1928592181    96
-0.0682975467    97   0.0044975289    98  -0.0126684490    99   0.0000000000   101
 0.0000000001   102   0.0000000001   103  -0.0000000005   104  -0.0865394521   105
-0.0000000001   107  -0.0003977754   108  -0.0000000001   110   0.0204636868   111
 0.0000000001   113  -0.0000000000   115  -0.0000000004   116  -0.0000000001   117
 0.0000000000   118  -0.0048836154   119
# ORBITAL         16  NAO =      90
-0.0003586348     1  -0.0220988824     2  -0.0279910890     3   0.0076641824     4
 0.1632676821     5   0.0290045303     7   0.0509421160     8   0.0106923614    10
 0.0119090275    11  -0.0128503064    13   0.0005575567    15   0.1113324509    16
 0.0394219179    17  -0.0074820090    18  -0.0044959757    19   0.0003586348    21
 0.0220988823    22   0.0279910887    23   0.0076641819    24  -0.1632676811    25
 0.0290045293    27  -0.0509421154    28  -0.0106923611    30   0.0119090285    31
 0.0128503057    33  -0.0005575565    35  -0.1113324506    36  -0.0394219177    37
-0.0074820091    38   0.0044959755    39   0.0007213416    41   0.0441838214    42
 0.0558579175    43   0.2904548744    44  -0.0000000001    45   0.1171902403    47
 0.0000000000    48  -0.0039203318    50  -0.0000000002    51   0.0082203577    53
-0.0011142396    55  -0.2227104062    56  -0.0788656304    57  -0.0152767920    58
 0.0000000001    59   0.0003586348    61   0.0220988824    62   0.0279910889    63
 0.0076641824    64   0.1632676819    65   0.0290045295    67   0.0509421156    68
-0.0106923610    70  -0.0119090285    71   0.0128503057    73  -0.0005575565    75
-0.1113324512    76  -0.0394219179    77  -0.0074820092    78  -0.0044959756    79
-0.0003586348    81  -0.0220988822    82  -0.0279910888    83   0.0076641819    84
-0.1632676816    85   0.0290045301    87  -0.0509421157    88   0.0106923615    90
-0.0119090275    91  -0.0128503065    93   0.0005575567    95   0.1113324502    96
 0.0394219176    97  -0.0074820090    98   0.0044959758    99  -0.0007213416   101
-0.0441838220   102  -0.0558579171   103   0.2904548721   104  -0.0000000001   105
 0.1171902421   107  -0.0000000000   108   0.0039203305   110  -0.0000000001   111
-0.0082203568   113   0.0011142407   115   0.2227104073   116   0.0788656318   117
-0.0152767901   118  -0.0000000001   119
# ORBITAL         17  NAO =      90
-0.0012911822     1  -0.0067578701     2   0.0010641979     3   0.2465963959     4
-0.0149150249     5   0.1010029777     7  -0.0041486050     8  -0.0213705643    10
 0.0047272710    11   0.0206865037    13   0.0003120959    15   0.1092296435    16
 0.0566451247    17   0.0032481770    18  -0.0081643699    19  -0.0012911822    21
-0.0067578703    22   0.0010641980    23  -0.2465963959    24  -0.0149150244    25
-0.1010029782    27  -0.0041486050    28  -0.0213705640    30  -0.0047272709    31
 0.0206865033    33   0.0003120959    35   0.1092296434    36   0.0566451249    37
-0.0032481772    38  -0.0081643701    39   0.0025873290    41   0.0136123011    42
-0.0020704704    43   0.2206386849    44   0.0000000000    45   0.0937752162    47
 0.0000000000    48  -0.0274275908    50  -0.0000000002    51   0.0288047866    53
-0.0006225099    55  -0.2183274679    56  -0.1132505770    57  -0.0108749007    58
 0.0000000001    59  -0.0012911822    61  -0.0067578702    62   0.0010641980    63
-0.2465963960    64   0.0149150247    65  -0.1010029780    67   0.0041486050    68
-0.0213705641    70   0.0047272710    71   0.0206865034    73   0.0003120959    75
 0.1092296434    76   0.0566451248    77  -0.0032481771    78   0.0081643701    79
-0.0012911822    81  -0.0067578700    82   0.0010641980    83   0.2465963959    84
 0.0149150247    85   0.1010029776    87   0.0041486049    88  -0.0213705644    90
-0.0047272711    91   0.0206865038    93   0.0003120960    95   0.1092296435    96
 0.0566451247    97   0.0032481769    98   0.0081643700    99   0.0025873290   101
 0.0136123017   102  -0.0020704709   103  -0.2206386828   104   0.0000000001   105
-0.0937752175   107   0.0000000001   108  -0.0274275902   110   0.0000000002   111
 0.0288047861   113  -0.0006225107   115  -0.2183274690   116  -0.1132505784   117
 0.0108748991   118   0.0000000001   119
# ORBITAL         18  NAO =      90
-0.0022422568     1  -0.0117861316     2   0.0017961586     3  -0.0149685697     4
 0.2293271422     5  -0.0041574297     7   0.0961923012     8  -0.0046743391    10
 0.0297488877    11   0.0035011315    13   0.0005353083    15   0.1890734811    16
 0.0980836424    17  -0.0081565837    18  -0.0061626988    19   0.0022422568    21
 0.0117861306    22  -0.0017961592    23  -0.0149685686    24  -0.2293271406    25
-0.0041574294    27  -0.0961923006    28   0.0046743386    30   0.0297488899    31
-0.0035011317    33  -0.0005353092    35  -0.1890734813    36  -0.0980836425    37
-0.0081565829    38   0.0061626996    39   0.0000000000    41  -0.0000000000    42
 0.0000000000    43   0.0000000001    44   0.2552406577    45   0.0000000001    47
 0.1034033602    48   0.0000000001    50   0.0215474843    51  -0.0000000000    53
 0.0000000001    55  -0.0000000000    56  -0.0000000000    57   0.0000000000    58
 0.0079649290    59  -0.0022422568    61  -0.0117861306    62   0.0017961592    63
 0.0149685685    64  -0.2293271407    65   0.0041574294    67  -0.0961923005    68
-0.0046743388    70   0.0297488900    71   0.0035011319    73   0.0005353091    75
 0.1890734813    76   0.0980836425    77   0.0081565830    78   0.0061626997    79
 0.0022422568    81   0.0117861315    82  -0.0017961586    83   0.0149685698    84
 0.2293271424    85   0.0041574298    87   0.0961923012    88   0.0046743391    90
 0.0297488876    91  -0.0035011315    93  -0.0005353084    95  -0.1890734810    96
-0.0980836423    97   0.0081565838    98  -0.0061626989    99   0.0000000000   101
 0.0000000000   102  -0.0000000000   103  -0.0000000000   104  -0.2552406531   105
-0.0000000000   107  -0.1034033615   108  -0.0000000001   110   0.0215474869   111
 0.0000000001   113  -0.0000000001   115  -0.0000000001   116  -0.0000000000   117
-0.0000000000   118  -0.0079649287   119
# ORBITAL         19  NAO =       5
-0.6069137242     6  -0.5288219485     9   0.0160778803    12   0.0278520511    14
-0.0182054019    20
# ORBITAL         20  NAO =       5
-0.6069137241    26  -0.5288219486    29  -0.0160778803    32   0.0278520509    34
-0.0182054020    40
# ORBITAL         21  NAO =       5
-0.6069128657    46  -0.5288236221    49  -0.0321586274    52   0.0000000002    54
-0.0182031846    60
# ORBITAL         22  NAO =       5
-0.6069137243    66  -0.5288219484    69  -0.0160778802    72  -0.0278520508    74
-0.0182054020    80
# ORBITAL         23  NAO =       5
-0.6069137243    86  -0.5288219484    89   0.0160778802    92  -0.0278520511    94
-0.0182054019   100
# ORBITAL         24  NAO =       5
-0.6069128633   106  -0.5288236244   109   0.0321586294   112   0.0000000002   114
-0.0182031848   120
$end

In the input file, VB structures are specified by the users rather than automatically generated. The keyword NSTR=2 in $CTRL section specifies 2 VB structures in the computation, and the 2 Kekulé structures are described in section $STR. The keyword GUESS=READ means that the initial guess is obtained by the user in $GUS section. The initial guess comes from the optmized orbitals of previous computation, stored in corresponding ORB file.

Computational Results

The final energy of the computation can be found after VBSCF iterations as -230.62995 hartree. Compared with the energy including 5 covalent structures, the corresponding resonance energy from Dewar structures can be obtained as 2.8 kcal/mol.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 C           2 H            1.093       0.979
 1 C           3 C            1.399       1.186
 3 C           4 H            1.093       0.979
 3 C           5 C            1.399       1.186
 5 C           6 H            1.093       0.979
 5 C           7 C            1.399       1.186
 7 C           8 H            1.093       0.979
 7 C           9 C            1.399       1.186
 9 C          10 H            1.093       0.979
 1 C          11 C            1.399       1.186
 9 C          11 C            1.399       1.186
11 C          12 H            1.093       0.979

The atomic population analysis also shows that the bonder orders of CC bondings are the same as 1.186. Compared with the bond order from 5 covalent structures and the resonance energy from Dewar structures, the conjugation and stability mainly come from the resonance of Kekulé structures.

Computations with 1 Kekulé Structure

Finally, the computation including only 1 Kekulé structure, which represents a cycloalkene, will be proceeded to check the resonance from Kekulé structures.

Input File

The input file of this computation is shown below. The initial guess comes from the optimized orbitals of the computation including 2 Kekulé structures.

C6H6
$ctrl
nstr=1 nao=6 nae=6 iprint=3
orbtyp=hao frgtyp=sao
basis=cc-pvdz
guess=read
$end
$str
1:18 19-24
$end
$frag
12 2*6
spxpydxxdyydzzdxy 1-12
pzdxzdyz 1 2
pzdxzdyz 3 4
pzdxzdyz 5 6
pzdxzdyz 7 8
pzdxzdyz 9 10
pzdxzdyz 11 12
$end
$orb
1*18 1*6
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
3
4
5
6
7
$end
$geo
 C           0.6995000584   1.2115696411   0.0000000000
 H           1.2460106991   2.1581538376   0.0000000000
 C          -0.6995000584   1.2115696411   0.0000000000
 H          -1.2460106991   2.1581538376   0.0000000000
 C          -1.3990001169   0.0000000000   0.0000000000
 H          -2.4920213982   0.0000000000   0.0000000000
 C          -0.6995000584  -1.2115696411   0.0000000000
 H          -1.2460106991  -2.1581538376   0.0000000000
 C           0.6995000584  -1.2115696411   0.0000000000
 H           1.2460106991  -2.1581538376   0.0000000000
 C           1.3990001169   0.0000000000   0.0000000000
 H           2.4920213982   0.0000000000   0.0000000000
$end
$gus
    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90    90     5     5     5     5     5     5
# ORBITAL          1  NAO =      90
-0.4085796783     1  -0.0018719283     2   0.0001665818     3   0.0001010685     4
 0.0001981258     5   0.0000450438     7   0.0000863179     8   0.0009553396    10
 0.0000836069    11   0.0010374634    13   0.0011387900    15  -0.0001957720    16
-0.0001340753    17   0.0000469703    18   0.0000827563    19  -0.4085796727    21
-0.0018719292    22   0.0001665812    23  -0.0001010727    24   0.0001981248    25
-0.0000450425    27   0.0000863186    28   0.0009553426    30  -0.0000836019    31
 0.0010374618    33   0.0011387887    35  -0.0001957726    36  -0.0001340767    37
-0.0000469715    38   0.0000827567    39  -0.4090835453    41  -0.0018962542    42
 0.0001483676    43  -0.0002144425    44   0.0000004419    45  -0.0001064444    47
 0.0000000620    48   0.0010795224    50  -0.0000005324    51   0.0009089949    53
 0.0011398054    55  -0.0002140828    56  -0.0001424123    57  -0.0000967357    58
 0.0000004933    59  -0.4085796762    61  -0.0018717962    62   0.0001665571    63
-0.0001012559    64  -0.0001976491    65  -0.0000451304    67  -0.0000860262    68
 0.0009554043    70   0.0000853899    71   0.0010374754    73   0.0011388868    75
-0.0001954373    76  -0.0001341537    77  -0.0000475649    78  -0.0000822130    79
-0.4085796747    81  -0.0018717874    82   0.0001665574    83   0.0001012488    84
-0.0001976456    85   0.0000451252    87  -0.0000860254    88   0.0009553937    90
-0.0000853972    91   0.0010374881    93   0.0011388931    95  -0.0001954365    96
-0.0001341565    97   0.0000475538    98  -0.0000822115    99  -0.4090835098   101
-0.0018962560   102   0.0001483691   103   0.0002144405   104   0.0000004455   105
 0.0001064418   107   0.0000000681   108   0.0010795349   110   0.0000005509   111
 0.0009089845   113   0.0011398035   115  -0.0002140768   116  -0.0001424127   117
 0.0000967353   118   0.0000005091   119
# ORBITAL          2  NAO =      90
 0.2888921826     1   0.0012283761     2  -0.0002515233     3   0.0001334436     4
-0.0001583616     5   0.0001866742     7  -0.0001486589     8  -0.0008194761    10
-0.0001545655    11  -0.0005903612    13  -0.0007993769    15   0.0001561841    16
 0.0000815611    17   0.0000143387    18  -0.0000796338    19  -0.2888922723    21
-0.0012282896    22   0.0002516068    23   0.0001334933    24   0.0001581461    25
 0.0001866825    27   0.0001482790    28   0.0008195384    30  -0.0001557097    31
 0.0005903305    33   0.0007993976    35  -0.0001560171    36  -0.0000815893    37
 0.0000140002    38   0.0000793106    39  -0.5781886874    41  -0.0024517953    42
 0.0004960627    43  -0.0001410124    44   0.0000000144    45  -0.0000703152    47
 0.0000000565    48   0.0015346481    50  -0.0000001631    51   0.0013051183    53
 0.0016011118    55  -0.0003076892    56  -0.0001586915    57  -0.0001240234    58
 0.0000001386    59  -0.2888922230    61  -0.0012282282    62   0.0002515995    63
 0.0001335274    64  -0.0001581270    65   0.0001867496    67  -0.0001482931    68
 0.0008194516    70   0.0001556375    71   0.0005904439    73   0.0007994395    75
-0.0001560266    76  -0.0000816204    77   0.0000141380    78  -0.0000793592    79
 0.2888922537    81   0.0012283054    82  -0.0002515181    83   0.0001334812    84
 0.0001583237    85   0.0001867191    87   0.0001486497    88  -0.0008194148    90
 0.0001546034    91  -0.0005904524    93  -0.0007994211    95   0.0001561754    96
 0.0000815940    97   0.0000144233    98   0.0000796423    99   0.5781886588   101
 0.0024515577   102  -0.0004959802   103  -0.0001409979   104  -0.0000000307   105
-0.0000705453   107  -0.0000000454   108  -0.0015343653   110  -0.0000001509   111
-0.0013054893   113  -0.0016012734   115   0.0003078240   116   0.0001587913   117
-0.0001239620   118  -0.0000001283   119
# ORBITAL          3  NAO =      90
 0.5006101737     1   0.0021131041     2  -0.0004386602     3  -0.0001720820     4
-0.0000537351     5  -0.0001544833     7   0.0000103521     8  -0.0010913048    10
-0.0000446596    11  -0.0013590329    13  -0.0013847882    15   0.0002530053    16
 0.0001361579    17  -0.0000788740    18  -0.0000770243    19   0.5006101452    21
 0.0021129625    22  -0.0004386520    23   0.0001720253    24  -0.0000536574    25
 0.0001543765    27   0.0000103495    28  -0.0010911679    30   0.0000446577    31
-0.0013592283    33  -0.0013848833    35   0.0002530062    36   0.0001362215    37
 0.0000786944    38  -0.0000770459    39  -0.0000000492    41  -0.0000000438    42
 0.0000000133    43  -0.0000000140    44   0.0002083475    45   0.0000000368    47
 0.0002656048    48   0.0000000488    50   0.0002187797    51  -0.0000000628    53
-0.0000000239    55   0.0000000279    56   0.0000000168    57  -0.0000000076    58
 0.0000604882    59  -0.5006102068    61  -0.0021129621    62   0.0004386735    63
-0.0001720307    64  -0.0000536122    65  -0.0001543752    67   0.0000104714    68
 0.0010911805    70   0.0000450132    71   0.0013592249    73   0.0013848909    75
-0.0002529465    76  -0.0001362288    77  -0.0000787963    78  -0.0000769463    79
-0.5006101688    81  -0.0021131026    82   0.0004386817    83   0.0001720878    84
-0.0000536878    85   0.0001544821    87   0.0000104746    88   0.0010913171    90
-0.0000450214    91   0.0013590299    93   0.0013847960    95  -0.0002529452    96
-0.0001361656    97   0.0000789791    98  -0.0000769196    99   0.0000000225   101
-0.0000000446   102   0.0000000134   103   0.0000000135   104   0.0002082166   105
-0.0000000368   107   0.0002654040   108   0.0000000506   110  -0.0002194550   111
-0.0000000653   113  -0.0000000248   115   0.0000000293   116   0.0000000173   117
 0.0000000083   118   0.0000599174   119
# ORBITAL          4  NAO =      90
-0.2893480425     1  -0.0011811095     2   0.0006744406     3   0.0001189419     4
-0.0000446067     5   0.0000569570     7  -0.0002197480     8   0.0005592017    10
-0.0000156074    11   0.0006968256    13   0.0007625480    15  -0.0000777904    16
-0.0000296491    17   0.0000238435    18   0.0000028641    19  -0.2893481096    21
-0.0011811399    22   0.0006744442    23  -0.0001189574    24  -0.0000445949    25
-0.0000569839    27  -0.0002197505    28   0.0005592352    30   0.0000155929    31
 0.0006967797    33   0.0007625291    35  -0.0000777899    36  -0.0000296344    37
-0.0000238983    38   0.0000028476    39   0.5779780421    41   0.0024236036    42
-0.0013095349    43  -0.0000033117    44  -0.0000000730    45  -0.0003415559    47
 0.0000000126    48  -0.0012987191    50   0.0000000214    51  -0.0012017051    53
-0.0015230608    55   0.0002233907    56   0.0000742468    57   0.0000352458    58
-0.0000000253    59  -0.2893480526    61  -0.0011811337    62   0.0006744475    63
-0.0001189109    64   0.0000445154    65  -0.0000569376    67   0.0002196894    68
 0.0005591878    70  -0.0000159673    71   0.0006968259    73   0.0007625328    75
-0.0000778596    76  -0.0000296337    77  -0.0000237314    78  -0.0000029671    79
-0.2893481027    81  -0.0011811672    82   0.0006744484    83   0.0001189251    84
 0.0000444960    85   0.0000569605    87   0.0002196888    88   0.0005592200    90
 0.0000159731    91   0.0006967804    93   0.0007625097    95  -0.0000778598    96
-0.0000296196    97   0.0000237689    98  -0.0000029652    99   0.5779780591   101
 0.0024236073   102  -0.0013095365   103   0.0000033130   104  -0.0000000990   105
 0.0003415570   107  -0.0000000336   108  -0.0012987290   110  -0.0000001709   111
-0.0012016972   113  -0.0015230594   115   0.0002233876   116   0.0000742455   117
-0.0000352451   118  -0.0000001515   119
# ORBITAL          5  NAO =      90
-0.5007499006     1  -0.0020932788     2   0.0011339536     3  -0.0000684881     4
 0.0000697482     5  -0.0002271535     7  -0.0001934040     8   0.0010981889    10
 0.0000685550    11   0.0010726975    13   0.0013215420    15  -0.0001608701    16
-0.0000525753    17   0.0000029695    18   0.0000308210    19   0.5007498476    21
 0.0020932696    22  -0.0011339307    23  -0.0000684705    24  -0.0000697471    25
-0.0002271239    27   0.0001933327    28  -0.0010982033    30   0.0000684523    31
-0.0010726842    33  -0.0013215463    35   0.0001608813    36   0.0000525762    37
 0.0000029679    38  -0.0000308358    39   0.0000000362    41  -0.0000000393    42
 0.0000000128    43  -0.0000000095    44   0.0001873871    45   0.0000000353    47
 0.0002028610    48   0.0000000422    50   0.0000930299    51  -0.0000000564    53
-0.0000000238    55   0.0000000220    56   0.0000000158    57  -0.0000000073    58
 0.0000255403    59  -0.5007498869    61  -0.0020932596    62   0.0011339537    63
 0.0000684717    64  -0.0000696927    65   0.0002271254    67   0.0001934495    68
 0.0010982216    70   0.0000687936    71   0.0010726748    73   0.0013215517    75
-0.0001608273    76  -0.0000525822    77  -0.0000030701    78  -0.0000307435    79
 0.5007498440    81   0.0020932955    82  -0.0011339306    83   0.0000684810    84
 0.0000698075    85   0.0002271480    87  -0.0001932870    88  -0.0010981803    90
 0.0000681955    91  -0.0010726973    93  -0.0013215327    95   0.0001609262    96
 0.0000525662    97  -0.0000028726    98   0.0000309235    99   0.0000000242   101
-0.0000000429   102   0.0000000121   103   0.0000000074   104  -0.0001872809   105
-0.0000000363   107  -0.0002028699   108   0.0000000512   110   0.0000931069   111
-0.0000000660   113  -0.0000000272   115   0.0000000283   116   0.0000000166   117
 0.0000000105   118  -0.0000254667   119
# ORBITAL          6  NAO =      90
 0.4091242805     1   0.0018190810     2  -0.0036449243     3   0.0000003109     4
-0.0000029945     5   0.0007740556     7   0.0013380065     8  -0.0007544593    10
 0.0000780477    11  -0.0006748974    13  -0.0009960142    15  -0.0000423640    16
-0.0002163202    17   0.0000245090    18   0.0000435846    19  -0.4091242314    21
-0.0018191745    22   0.0036448420    23   0.0000002969    24   0.0000032856    25
 0.0007740526    27  -0.0013375548    28   0.0007543969    30   0.0000795334    31
 0.0006749172    33   0.0009959764    35   0.0000421336    36   0.0002163607    37
 0.0000249463    38  -0.0000431647    39   0.4088374571    41   0.0018140837    42
-0.0036448324    43   0.0000011734    44   0.0000001409    45  -0.0015470931    47
 0.0000001187    48  -0.0006363791    50  -0.0000004489    51  -0.0007950336    53
-0.0009967424    55  -0.0000464723    56  -0.0002169062    57  -0.0000506419    58
 0.0000003853    59  -0.4091242365    61  -0.0018190027    62   0.0036448289    63
 0.0000003326    64  -0.0000031321    65   0.0007741531    67   0.0013375953    68
 0.0007542579    70  -0.0000792764    71   0.0006751316    73   0.0009960980    75
 0.0000421797    76   0.0002162805    77   0.0000250537    78   0.0000432185    79
 0.4091242781    81   0.0018189398    82  -0.0036449221    83   0.0000004009    84
 0.0000029779    85   0.0007741877    87  -0.0013379594    88  -0.0007542979    90
-0.0000783208    91  -0.0006751119    93  -0.0009961062    95  -0.0000423138    96
-0.0002162634    97   0.0000247982    98  -0.0000434744    99  -0.4088374402   101
-0.0018138102   102   0.0036447434   103   0.0000011435   104  -0.0000000067   105
-0.0015468397   107  -0.0000001002   108   0.0006360602   110  -0.0000002972   111
 0.0007954525   113   0.0009969239   115   0.0000463126   116   0.0002167944   117
-0.0000507097   118  -0.0000002434   119
# ORBITAL          7  NAO =      90
-0.0105310908     1   0.1791319489     2   0.0923971303     3  -0.0318962677     4
-0.0553214746     5  -0.0062990419     7  -0.0109406130     8   0.0108261423    10
-0.0038130194    11   0.0070179874    13  -0.0063573590    15   0.0456220599    16
 0.0036425281    17  -0.0036155711    18  -0.0062523687    19  -0.0105314089    21
 0.1791319474    22   0.0923971349    23   0.0318962676    24  -0.0553214745    25
 0.0062990427    27  -0.0109406141    28   0.0108261425    30   0.0038130195    31
 0.0070179875    33  -0.0063573581    35   0.0456220596    36   0.0036425283    37
 0.0036155718    38  -0.0062523691    39  -0.0106286110    41   0.1791775670    42
 0.0924119143    43   0.0638644527    44  -0.0000000012    45   0.0126250153    47
-0.0000000001    48   0.0051125578    50   0.0000000011    51   0.0127368885    53
-0.0063570874    55   0.0456280497    56   0.0036351310    57   0.0072220519    58
-0.0000000009    59  -0.0105311113    61   0.1791319485    62   0.0923971342    63
 0.0318962682    64   0.0553214734    65   0.0062990428    67   0.0109406133    68
 0.0108261418    70  -0.0038130232    71   0.0070179867    73  -0.0063573593    75
 0.0456220589    76   0.0036425285    77   0.0036155729    78   0.0062523682    79
-0.0105311036    81   0.1791319484    82   0.0923971305    83  -0.0318962682    84
 0.0553214734    85  -0.0062990421    87   0.0109406123    88   0.0108261422    90
 0.0038130230    91   0.0070179872    93  -0.0063573596    95   0.0456220592    96
 0.0036425281    97  -0.0036155721    98   0.0062523679    99  -0.0106297497   101
 0.1791775616   102   0.0924119206   103  -0.0638644524   104  -0.0000000012   105
-0.0126250177   107  -0.0000000000   108   0.0051125593   110  -0.0000000010   111
 0.0127368898   113  -0.0063570850   115   0.0456280500   116   0.0036351304   117
-0.0072220520   118  -0.0000000009   119
# ORBITAL          8  NAO =      90
 0.0076028895     1  -0.1247833094     2  -0.0702498150     3  -0.0785132216     4
 0.0639777661     5  -0.0281449519     7   0.0270091285     8   0.0056384214    10
 0.0119231520    11  -0.0143970361    13   0.0039295681    15  -0.0517335466    16
-0.0069559347    17   0.0014213923    18   0.0074921988    19  -0.0076028888    21
 0.1247833182    22   0.0702498194    23  -0.0785132193    24  -0.0639777657    25
-0.0281449519    27  -0.0270091281    28  -0.0056384209    30   0.0119231587    31
 0.0143970362    33  -0.0039295685    35   0.0517335493    36   0.0069559353    37
 0.0014213952    38  -0.0074922001    39  -0.0151821569    41   0.2495710190    42
 0.1404874823    43   0.0322982227    44   0.0000000019    45   0.0186231256    47
 0.0000000007    48   0.0009086803    50   0.0000000010    51   0.0166300085    53
-0.0078591029    55   0.1034526736    56   0.0139125616    57   0.0143887842    58
-0.0000000004    59  -0.0076028851    61   0.1247833096    62   0.0702498147    63
-0.0785132218    64   0.0639777655    65  -0.0281449531    67   0.0270091281    68
-0.0056384214    70  -0.0119231586    71   0.0143970359    73  -0.0039295685    75
 0.0517335459    76   0.0069559349    77   0.0014213945    78   0.0074921998    79
 0.0076028868    81  -0.1247833174    82  -0.0702498196    83  -0.0785132191    84
-0.0639777655    85  -0.0281449509    87  -0.0270091286    88   0.0056384206    90
-0.0119231525    91  -0.0143970358    93   0.0039295688    95  -0.0517335500    96
-0.0069559352    97   0.0014213925    98  -0.0074921991    99   0.0151821472   101
-0.2495710187   102  -0.1404874829   103   0.0322982228   104   0.0000000027   105
 0.0186231264   107   0.0000000008   108  -0.0009086819   110   0.0000000004   111
-0.0166300072   113   0.0078591049   115  -0.1034526738   116  -0.0139125612   117
 0.0143887828   118   0.0000000005   119
# ORBITAL          9  NAO =      90
 0.0131251465     1  -0.2161385559     2  -0.1216727085     3   0.0639730896     4
-0.0046068035     5   0.0270059763     7   0.0030477106     8  -0.0179156928    10
 0.0021926302    11   0.0027320071    13   0.0068069785    15  -0.0895734340    16
-0.0120431889    17   0.0074864530    18   0.0100635578    19   0.0131251217    21
-0.2161385511    22  -0.1216727056    23  -0.0639730923    24  -0.0046068060    25
-0.0270059769    27   0.0030477096    28  -0.0179156936    30  -0.0021926297    31
 0.0027320083    33   0.0068069785    35  -0.0895734318    36  -0.0120431888    37
-0.0074864525    38   0.0100635578    39  -0.0000000465    41   0.0000000049    42
 0.0000000028    43   0.0000000007    44  -0.1154806636    45   0.0000000001    47
-0.0437490908    48  -0.0000000002    50  -0.0184557093    51   0.0000000009    53
 0.0000000000    55   0.0000000019    56   0.0000000002    57   0.0000000004    58
-0.0029085310    59  -0.0131252134    61   0.2161385558    62   0.1216727087    63
 0.0639730895    64  -0.0046068039    65   0.0270059757    67   0.0030477102    68
 0.0179156937    70  -0.0021926324    71  -0.0027320077    73  -0.0068069787    75
 0.0895734335    76   0.0120431889    77   0.0074864531    78   0.0100635579    79
-0.0131251919    81   0.2161385514    82   0.1216727057    83  -0.0639730926    84
-0.0046068062    85  -0.0270059772    87   0.0030477091    88   0.0179156935    90
 0.0021926320    91  -0.0027320077    93  -0.0068069785    95   0.0895734316    96
 0.0120431885    97  -0.0074864534    98   0.0100635574    99  -0.0000000629   101
-0.0000000047   102  -0.0000000024   103   0.0000000005   104  -0.1154806635   105
 0.0000000006   107  -0.0437490900   108  -0.0000000003   110   0.0184557112   111
 0.0000000003   113   0.0000000003   115  -0.0000000021   116  -0.0000000004   117
 0.0000000002   118  -0.0029085291   119
# ORBITAL         10  NAO =      90
-0.0049057145     1   0.1006640065     2   0.0846904205     3  -0.1397564545     4
 0.1141784842     5  -0.0456691919     7   0.0234357582     8   0.0117723759    10
 0.0056723402    11  -0.0100538947    13  -0.0019191218    15   0.0770189499    16
 0.0164355039    17  -0.0072749056    18  -0.0060278708    19  -0.0049056971    21
 0.1006640036    22   0.0846904176    23   0.1397564569    24   0.1141784844    25
 0.0456691926    27   0.0234357589    28   0.0117723756    30  -0.0056723405    31
-0.0100538947    33  -0.0019191215    35   0.0770189473    36   0.0164355032    37
 0.0072749056    38  -0.0060278707    39   0.0099053219    41  -0.2012723368    42
-0.1693914578    43   0.0583006645    44  -0.0000000021    45  -0.0049813010    47
-0.0000000006    48   0.0007093782    50  -0.0000000002    51  -0.0041287655    53
 0.0038346686    55  -0.1542323428    56  -0.0329233571    57  -0.0177384123    58
-0.0000000001    59  -0.0049057294    61   0.1006640075    62   0.0846904208    63
 0.1397564543    64  -0.1141784844    65   0.0456691920    67  -0.0234357583    68
 0.0117723757    70   0.0056723403    71  -0.0100538948    73  -0.0019191218    75
 0.0770189499    76   0.0164355037    77   0.0072749057    78   0.0060278712    79
-0.0049057266    81   0.1006640034    82   0.0846904175    83  -0.1397564568    84
-0.1141784844    85  -0.0456691923    87  -0.0234357585    88   0.0117723760    90
-0.0056723404    91  -0.0100538949    93  -0.0019191216    95   0.0770189470    96
 0.0164355031    97  -0.0072749055    98   0.0060278709    99   0.0099053293   101
-0.2012723391   102  -0.1693914579   103  -0.0583006644   104   0.0000000023   105
 0.0049813014   107   0.0000000005   108   0.0007093780   110   0.0000000002   111
-0.0041287656   113   0.0038346685   115  -0.1542323426   116  -0.0329233566   117
 0.0177384131   118   0.0000000002   119
# ORBITAL         11  NAO =      90
-0.0085816245     1   0.1743307075     2   0.1466700542     3   0.1142616239     4
-0.0078017212     5   0.0234796112     7  -0.0185688373     8  -0.0034134122    10
-0.0060578410    11   0.0063987626    13  -0.0033214565    15   0.1334722320    16
 0.0284803972    17  -0.0060295874    18  -0.0142387079    19   0.0085817066    21
-0.1743307092    22  -0.1466700558    23   0.1142616215    24   0.0078017193    25
 0.0234796105    27   0.0185688370    28   0.0034134117    30  -0.0060578404    31
-0.0063987626    33   0.0033214561    35  -0.1334722334    36  -0.0284803975    37
-0.0060295876    38   0.0142387083    39   0.0000000232    41   0.0000000025    42
 0.0000000015    43  -0.0000000006    44  -0.2057189432    45  -0.0000000001    47
-0.0592113756    48  -0.0000000002    50  -0.0158769336    51   0.0000000002    53
-0.0000000002    55   0.0000000016    56   0.0000000002    57   0.0000000002    58
-0.0037955897    59  -0.0085818294    61   0.1743307067    62   0.1466700548    63
-0.1142616247    64   0.0078017211    65  -0.0234796110    67   0.0185688378    68
-0.0034134117    70  -0.0060578412    71   0.0063987630    73  -0.0033214559    75
 0.1334722315    76   0.0284803970    77   0.0060295877    78   0.0142387083    79
 0.0085817260    81  -0.1743307096    82  -0.1466700567    83  -0.1142616213    84
-0.0078017187    85  -0.0234796100    87  -0.0185688372    88   0.0034134116    90
-0.0060578408    91  -0.0063987625    93   0.0033214565    95  -0.1334722335    96
-0.0284803973    97   0.0060295877    98  -0.0142387085    99   0.0000000049   101
 0.0000000018   102   0.0000000020   103   0.0000000006   104   0.2057189443   105
-0.0000000002   107   0.0592113755   108   0.0000000002   110  -0.0158769330   111
-0.0000000001   113   0.0000000002   115   0.0000000015   116   0.0000000004   117
-0.0000000002   118   0.0037955897   119
# ORBITAL         12  NAO =      90
-0.0036804733     1   0.0117300772     2   0.0327949959     3   0.0945818191     4
 0.1639064451     5   0.0323475941     7   0.0560232362     8   0.0005071356    10
-0.0050238617    11  -0.0045215349    13   0.0010077685    15   0.1492702225    16
 0.0353806840    17  -0.0067287801    18  -0.0116586245    19  -0.0036801487    21
 0.0117300780    22   0.0327949909    23  -0.0945818188    24   0.1639064458    25
-0.0323475949    27   0.0560232372    28   0.0005071356    30   0.0050238619    31
-0.0045215352    33   0.0010077677    35   0.1492702221    36   0.0353806834    37
 0.0067287796    38  -0.0116586240    39  -0.0037706044    41   0.0115958520    42
 0.0326192354    43  -0.1891354471    44  -0.0000000001    45  -0.0646757241    47
 0.0000000000    48  -0.0070415642    50   0.0000000004    51   0.0030215816    53
 0.0010143114    55   0.1491037933    56   0.0353238319    57   0.0134440798    58
-0.0000000003    59  -0.0036804485    61   0.0117300767    62   0.0327949914    63
-0.0945818192    64  -0.1639064466    65  -0.0323475947    67  -0.0560232367    68
 0.0005071362    70  -0.0050238629    71  -0.0045215347    73   0.0010077684    75
 0.1492702215    76   0.0353806829    77   0.0067287799    78   0.0116586241    79
-0.0036804586    81   0.0117300775    82   0.0327949955    83   0.0945818193    84
-0.1639064457    85   0.0323475941    87  -0.0560232360    88   0.0005071357    90
 0.0050238628    91  -0.0045215349    93   0.0010077686    95   0.1492702219    96
 0.0353806835    97  -0.0067287807    98   0.0116586245    99  -0.0037694668   101
 0.0115958596   102   0.0326192295   103   0.1891354472   104  -0.0000000001   105
 0.0646757261   107   0.0000000000   108  -0.0070415657   110  -0.0000000006   111
 0.0030215803   113   0.0010143087   115   0.1491037928   116   0.0353238322   117
-0.0134440812   118  -0.0000000004   119
# ORBITAL         13  NAO =      90
-0.0075512224     1   0.1114726348     2   0.1678599129     3   0.0636737890     4
 0.1102660175     5   0.0071157447     7   0.0123065687     8  -0.0147668118    10
 0.0206625187    11   0.0059162564    13   0.0000670171    15   0.1838227411    16
 0.0692803796    17  -0.0071326782    18  -0.0123576817    19   0.0075512222    21
-0.1114726347    22  -0.1678599129    23   0.0636737893    24  -0.1102660177    25
 0.0071157446    27  -0.0123065681    28   0.0147668120    30   0.0206625205    31
-0.0059162565    33  -0.0000670170    35  -0.1838227417    36  -0.0692803795    37
-0.0071326779    38   0.0123576821    39  -0.0075377798    41   0.1114776373    42
 0.1678699600    43  -0.1273340648    44   0.0000000002    45  -0.0142192259    47
 0.0000000000    48   0.0162548947    50  -0.0000000003    51  -0.0250878035    53
 0.0000679682    55   0.1838193396    56   0.0692809136    57   0.0142604356    58
 0.0000000003    59   0.0075512263    61  -0.1114726350    62  -0.1678599130    63
 0.0636737898    64   0.1102660184    65   0.0071157445    67   0.0123065680    68
 0.0147668119    70  -0.0206625199    71  -0.0059162563    73  -0.0000670168    75
-0.1838227412    76  -0.0692803792    77  -0.0071326782    78  -0.0123576825    79
-0.0075512249    81   0.1114726350    82   0.1678599130    83   0.0636737895    84
-0.1102660178    85   0.0071157447    87  -0.0123065685    88  -0.0147668117    90
-0.0206625190    91   0.0059162561    93   0.0000670170    95   0.1838227409    96
 0.0692803794    97  -0.0071326781    98   0.0123576822    99   0.0075377838   101
-0.1114776371   102  -0.1678699601   103  -0.1273340659   104   0.0000000001   105
-0.0142192253   107  -0.0000000000   108  -0.0162548953   110   0.0000000000   111
 0.0250878041   113  -0.0000679680   115  -0.1838193399   116  -0.0692809135   117
 0.0142604366   118  -0.0000000000   119
# ORBITAL         14  NAO =      90
-0.0000242668     1   0.0000211338     2   0.0000197397     3  -0.2396956057     4
 0.1383354950     5  -0.0832832747     7   0.0480626417     8   0.0082077199    10
 0.0054692760    11  -0.0082072207    13  -0.0000008338    15  -0.0000306106    16
-0.0000082652    17  -0.0045627706    18   0.0026348910    19  -0.0000242928    21
 0.0000211338    22   0.0000197399    23   0.2396956060    24   0.1383354958    25
 0.0832832749    27   0.0480626416    28   0.0082077197    30  -0.0054692758    31
-0.0082072205    33  -0.0000008342    35  -0.0000306103    36  -0.0000082653    37
 0.0045627709    38   0.0026348912    39   0.0000000316    41   0.0000000004    42
 0.0000000001    43   0.0000000000    44  -0.2767109921    45   0.0000000000    47
-0.0961484641    48  -0.0000000002    50  -0.0109288348    51  -0.0000000001    53
-0.0000000002    55   0.0000000000    56   0.0000000000    57   0.0000000000    58
-0.0052653392    59   0.0000243486    61  -0.0000211336    62  -0.0000197401    63
-0.2396956060    64   0.1383354959    65  -0.0832832749    67   0.0480626415    68
-0.0082077198    70  -0.0054692758    71   0.0082072205    73   0.0000008342    75
 0.0000306102    76   0.0000082652    77  -0.0045627709    78   0.0026348913    79
 0.0000243167    81  -0.0000211335    82  -0.0000197398    83   0.2396956060    84
 0.1383354953    85   0.0832832746    87   0.0480626416    88  -0.0082077199    90
 0.0054692764    91   0.0082072205    93   0.0000008337    95   0.0000306105    96
 0.0000082651    97   0.0045627706    98   0.0026348910    99   0.0000000566   101
 0.0000000007   102  -0.0000000000   103  -0.0000000000   104  -0.2767109937   105
 0.0000000000   107  -0.0961484638   108  -0.0000000005   110   0.0109288338   111
 0.0000000001   113  -0.0000000005   115   0.0000000001   116  -0.0000000001   117
-0.0000000000   118  -0.0052653392   119
# ORBITAL         15  NAO =      90
-0.0009983767     1  -0.0386214684     2  -0.0485455904     3   0.1633421841     4
 0.1962473237     5   0.0509807373     7   0.0877733678     8  -0.0121832761    10
 0.0001162009    11   0.0084147730    13   0.0010223542    15   0.1927411229    16
 0.0682210653    17  -0.0045132574    18  -0.0126863282    19  -0.0009983769    21
-0.0386214683    22  -0.0485455906    23  -0.1633421842    24   0.1962473245    25
-0.0509807372    27   0.0877733679    28  -0.0121832762    30  -0.0001162008    31
 0.0084147732    33   0.0010223542    35   0.1927411233    36   0.0682210653    37
 0.0045132578    38  -0.0126863281    39   0.0000000963    41   0.0000000005    42
 0.0000000001    43  -0.0000000002    44  -0.0868168628    45  -0.0000000004    47
-0.0005743185    48  -0.0000000005    50  -0.0204836282    51   0.0000000001    53
-0.0000000004    55   0.0000000002    56   0.0000000002    57   0.0000000001    58
-0.0048842722    59   0.0009985499    61   0.0386214692    62   0.0485455904    63
 0.1633421850    64   0.1962473253    65   0.0509807366    67   0.0877733671    68
 0.0121832762    70  -0.0001162013    71  -0.0084147740    73  -0.0010223547    75
-0.1927411227    76  -0.0682210647    77  -0.0045132580    78  -0.0126863286    79
 0.0009985050    81   0.0386214693    82   0.0485455908    83  -0.1633421847    84
 0.1962473254    85  -0.0509807370    87   0.0877733675    88   0.0121832760    90
 0.0001162015    91  -0.0084147736    93  -0.0010223547    95  -0.1927411232    96
-0.0682210651    97   0.0045132576    98  -0.0126863286    99   0.0000001212   101
 0.0000000009   102  -0.0000000000   103  -0.0000000009   104  -0.0868168632   105
 0.0000000001   107  -0.0005743183   108  -0.0000000006   110   0.0204836287   111
 0.0000000000   113  -0.0000000004   115  -0.0000000005   116  -0.0000000001   117
-0.0000000000   118  -0.0048842716   119
# ORBITAL         16  NAO =      90
-0.0005894251     1  -0.0223088039     2  -0.0280654665     3   0.0075643177     4
 0.1633898810     5   0.0288954659     7   0.0510111520     8   0.0106960596    10
 0.0118868073    11  -0.0128757602    13   0.0005926770    15   0.1112764638    16
 0.0393823208    17  -0.0074782289    18  -0.0045126110    19   0.0005894222    21
 0.0223088033    22   0.0280654662    23   0.0075643166    24  -0.1633898807    25
 0.0288954662    27  -0.0510111513    28  -0.0106960596    30   0.0118868066    31
 0.0128757604    33  -0.0005926768    35  -0.1112764634    36  -0.0393823205    37
-0.0074782291    38   0.0045126111    39   0.0011830149    41   0.0446313651    42
 0.0560606696    43   0.2905583224    44   0.0000000000    45   0.1172071367    47
 0.0000000000    48  -0.0038785631    50  -0.0000000003    51   0.0082267364    53
-0.0011834653    55  -0.2225345572    56  -0.0787777804    57  -0.0152898732    58
 0.0000000001    59   0.0005894244    61   0.0223088033    62   0.0280654664    63
 0.0075643175    64   0.1633898819    65   0.0288954663    67   0.0510111514    68
-0.0106960595    70  -0.0118868065    71   0.0128757604    73  -0.0005926768    75
-0.1112764638    76  -0.0393823205    77  -0.0074782294    78  -0.0045126114    79
-0.0005894255    81  -0.0223088036    82  -0.0280654663    83   0.0075643174    84
-0.1633898808    85   0.0288954658    87  -0.0510111516    88   0.0106960598    90
-0.0118868073    91  -0.0128757604    93   0.0005926770    95   0.1112764630    96
 0.0393823204    97  -0.0074782290    98   0.0045126113    99  -0.0011830119   101
-0.0446313639   102  -0.0560606692   103   0.2905583232   104  -0.0000000002   105
 0.1172071362   107  -0.0000000001   108   0.0038785629   110  -0.0000000005   111
-0.0082267365   113   0.0011834651   115   0.2225345571   116   0.0787777798   117
-0.0152898742   118  -0.0000000002   119
# ORBITAL         17  NAO =      90
-0.0014020326     1  -0.0068956525     2   0.0009658087     3   0.2467463560     4
-0.0150840636     5   0.1010428983     7  -0.0041186505     8  -0.0213912436    10
 0.0047152733    11   0.0207049577    13   0.0003249521    15   0.1090368977    16
 0.0565120453    17   0.0032595528    18  -0.0081550919    19  -0.0014020678    21
-0.0068956523    22   0.0009658091    23  -0.2467463563    24  -0.0150840638    25
-0.1010428983    27  -0.0041186508    28  -0.0213912436    30  -0.0047152734    31
 0.0207049580    33   0.0003249521    35   0.1090368981    36   0.0565120453    37
-0.0032595527    38  -0.0081550918    39   0.0028093586    41   0.0137482733    42
-0.0019741520    43   0.2207188322    44  -0.0000000000    45   0.0939446698    47
 0.0000000001    48  -0.0274316281    50  -0.0000000006    51   0.0288061575    53
-0.0006463540    55  -0.2181730829    56  -0.1130340303    57  -0.0108702108    58
 0.0000000003    59  -0.0014020302    61  -0.0068956520    62   0.0009658091    63
-0.2467463568    64   0.0150840636    65  -0.1010428979    67   0.0041186509    68
-0.0213912440    70   0.0047152734    71   0.0207049583    73   0.0003249522    75
 0.1090368979    76   0.0565120450    77  -0.0032595523    78   0.0081550920    79
-0.0014020296    81  -0.0068956524    82   0.0009658087    83   0.2467463565    84
 0.0150840633    85   0.1010428980    87   0.0041186504    88  -0.0213912437    90
-0.0047152733    91   0.0207049580    93   0.0003249522    95   0.1090368978    96
 0.0565120452    97   0.0032595526    98   0.0081550920    99   0.0028092657   101
 0.0137482731   102  -0.0019741520   103  -0.2207188329   104   0.0000000001   105
-0.0939446697   107   0.0000000002   108  -0.0274316280   110   0.0000000006   111
 0.0288061582   113  -0.0006463534   115  -0.2181730832   116  -0.1130340301   117
 0.0108702120   118   0.0000000003   119
# ORBITAL         18  NAO =      90
-0.0023749933     1  -0.0118884368     2   0.0017334005     3  -0.0150505701     4
 0.2293750064     5  -0.0041065876     7   0.0962994757     8  -0.0046652132    10
 0.0297409795    11   0.0034826782    13   0.0005612091    15   0.1889435721    16
 0.0978899218    17  -0.0081612949    18  -0.0061659303    19   0.0023750060    21
 0.0118884365    22  -0.0017334006    23  -0.0150505706    24  -0.2293750071    25
-0.0041065875    27  -0.0962994755    28   0.0046652135    30   0.0297409784    31
-0.0034826783    33  -0.0005612086    35  -0.1889435720    36  -0.0978899215    37
-0.0081612954    38   0.0061659300    39   0.0000000032    41   0.0000000001    42
-0.0000000001    43   0.0000000002    44   0.2554222892    45   0.0000000000    47
 0.1034266384    48   0.0000000003    50   0.0215760829    51  -0.0000000002    53
 0.0000000002    55  -0.0000000000    56  -0.0000000001    57  -0.0000000001    58
 0.0079574230    59  -0.0023750295    61  -0.0118884363    62   0.0017334008    63
 0.0150505703    64  -0.2293750078    65   0.0041065877    67  -0.0962994753    68
-0.0046652137    70   0.0297409788    71   0.0034826785    73   0.0005612087    75
 0.1889435718    76   0.0978899212    77   0.0081612957    78   0.0061659304    79
 0.0023750118    81   0.0118884367    82  -0.0017334007    83   0.0150505701    84
 0.2293750071    85   0.0041065877    87   0.0962994753    88   0.0046652134    90
 0.0297409792    91  -0.0034826785    93  -0.0005612092    95  -0.1889435718    96
-0.0978899216    97   0.0081612954    98  -0.0061659305    99   0.0000000018   101
 0.0000000003   102   0.0000000001   103   0.0000000001   104  -0.2554222907   105
 0.0000000000   107  -0.1034266382   108  -0.0000000003   110   0.0215760822   111
 0.0000000001   113  -0.0000000004   115   0.0000000000   116  -0.0000000001   117
 0.0000000000   118  -0.0079574229   119
# ORBITAL         19  NAO =       5
-0.6051361517     6  -0.5306934722     9   0.0161429500    12   0.0279606935    14
-0.0181292011    20
# ORBITAL         20  NAO =       5
-0.6051361519    26  -0.5306934721    29  -0.0161429499    32   0.0279606936    34
-0.0181292011    40
# ORBITAL         21  NAO =       5
-0.6051369321    46  -0.5306928695    49  -0.0322859902    52   0.0000000004    54
-0.0181286009    60
# ORBITAL         22  NAO =       5
-0.6051361524    66  -0.5306934715    69  -0.0161429500    72  -0.0279606933    74
-0.0181292011    80
# ORBITAL         23  NAO =       5
-0.6051361522    86  -0.5306934717    89   0.0161429499    92  -0.0279606934    94
-0.0181292011   100
# ORBITAL         24  NAO =       5
-0.6051369320   106  -0.5306928697   109   0.0322859897   112   0.0000000007   114
-0.0181286008   120
$end

Computational Results

The final energy can be found as -230.59097 hartree, and the resonance Kekulé structures is 24.5 kcal/mol, which is the stablization energy to delocalize the \(\pi\) orbitals in a cycloalkene.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 C           2 H            1.093       0.980
 1 C           3 C            1.399       1.425
 3 C           4 H            1.093       0.980
 3 C           5 C            1.399       1.011
 5 C           6 H            1.093       0.980
 5 C           7 C            1.399       1.425
 7 C           8 H            1.093       0.980
 7 C           9 C            1.399       1.012
 9 C          10 H            1.093       0.980
 1 C          11 C            1.399       1.011
 9 C          11 C            1.399       1.425
11 C          12 H            1.093       0.980

The bond orders show that the CC bondings are not equivalent now, there are 3 CC bondings with bond order 1.425, close to double bonding, and 3 bondings with 1.011, close to single bonding. The computational results suggest that the resonance from Kekulé structrues mainly stabilizes the molecule and makes all CC bondings equivalent. Both resonance from Kekulé structures and equalization of CC bonds thus present the aromaticity in C6H6.

Computing of O2

Introduction

The calculation of ground spin state of O2 has been an enduring topic in the early stages of the development of quantum chemistry. The ground state of O2 is triplet (\(^3\Sigma_g^{-}\)) from experiments. One of the most well-known “failure” of VB theory is that the ground state of O2 molecule is predicted as \(^1\Delta_g\) with VB theory. Here we clarify again that the so-called “failure” comes from the naive application of hybridization followed by the simple Lewis pairing. The ab initio VB calculation is capable of correctly describing the ground state of O2. In this section, both the triplet and singlet ground states of O2 will be computed and compared.

Computations of the singlet state

The computations are proceeded at the equilibrium bond length of 1.227 Å, and the basis set is cc-pVDZ. For simplicity, O atoms are located in the Z axis. Totally 4 active oritals (\(p_x\) and \(p_y\) orbitals of each O atom) and the 6 active electrons on them are inclued in the calculation. (Readers can also include the two \(p_z\) orbitals in the active space, but only the four mentioned \(p_{\pi}\) orbitals are included in this case)

Input File

Here shows the XMVB input file for all the structures

singlet O2 VBSCF with all structures
$CTRL
STR=FULL NAO=4 NAE=6 IPRINT=3
ORBTYP=HAO FRGTYP=SAO
BASIS=CC-PVDZ NMUL=1
GUESS=READ
$END
$FRAG
1*6
SPZDXXDYYDZZ 1
SPZDXXDYYDZZ 2
PXDXZ 1
PXDXZ 2
PYDYZ 1
PYDYZ 2
$END
$ORB
1*4 2 1*4
1
2
1
2
1 2
3
4
5
6
$END
$GEO
O 0.0 0.0 0.0
O 0.0 0.0 1.227
$END
$GUS
     8     8     8     8    16     3     3     3     3
# ORBITAL          1  NAO =       8
-1.0001816769     1  -0.0219071559     2  -0.0208718204     3   0.0055675373     6
 0.0058885238     9   0.0012121651    10   0.0012098650    13   0.0014914363    15
# ORBITAL          2  NAO =       8
-1.0001807197    16  -0.0219222377    17  -0.0208875165    18  -0.0055748376    21
-0.0058896710    24   0.0012101317    25   0.0012115362    28   0.0014916466    30
# ORBITAL          3  NAO =       8
-0.0380292983     1   0.4956131485     2   0.5430800220     3  -0.1721288256     6
-0.1265645521     9   0.0040244173    10   0.0040243680    13  -0.0013604634    15
# ORBITAL          4  NAO =       8
-0.0380587693    16   0.4956124042    17   0.5430787036    18   0.1721299458    21
 0.1265653159    24   0.0040244421    25   0.0040243828    28  -0.0013600709    30
# ORBITAL          5  NAO =      16
-0.1873055284     1  -0.0320312577     2   0.1037620245     3  -0.7575342039     6
-0.1745797408     9   0.0069166781    10   0.0069169372    13  -0.0385887223    15
-0.1873136771    16  -0.0320328992    17   0.1037594786    18   0.7575341385    21
 0.1745797704    24   0.0069172963    25   0.0069171279    28  -0.0385889746    30
# ORBITAL          6  NAO =       3
 0.6907525874     4   0.4550551271     7   0.0256096827    12
# ORBITAL          7  NAO =       3
 0.6907525665    19   0.4550551519    22  -0.0256096585    27
# ORBITAL          8  NAO =       3
 0.6907525875     5   0.4550551269     8   0.0256096869    14
# ORBITAL          9  NAO =       3
 0.6907525683    20   0.4550551500    23  -0.0256096533    29
$END

The global keywords listed in $CTRL section are explained below:

  • STR=FULL XMVB generates all VB structures automatically according to a specific active space.

  • IPRINT=3 XMVB will print most information.

  • NAO=4 and NAE=6 Specify the active space with 4 active orbital and 6 active electrons respectively.

  • ORBTYP=HAO and FRGTYP=SAO The VB orbitals are described with fragments.

  • BASIS=CC-PVDZ The basis set is cc-pVDZ.

  • NMUL=1 The spin multiplicity (2S+1) is 1 (The default value).

$FRAG section describes the fragments used to construct VB orbitals. In this case, the first line 1*6 means that there are 6 fragments built and each fragment include only 1 atom. The details of fragments are described in the following lines. For example, SPZDXXDYYDZZ 1 means that the fragment includes s, pz, dxx, dyy and dzz basis functions on atom 1, which is the first F atom in this case.

$ORB section describes VB orbitals. The first line 1*4 2 1*4 means that there are 9 orbitals in this case, each of the first 4 orbitals consisting of only 1 fragment, the 5th orbital consisting of 2 fragments, and each of the remaining 4 orbitals consisting of only 1 fragment. Each line below describes one orbital. For example, the first orbital includes only fragment 1, meaning that this orbital locates on the first O atom and belongs to the \(\sigma\) space since the O-O lies on Z axis. Also, orbital 5 with fragment 1 2 shows that the orbital describes the O-O sigma bonding orbital.

$GEO section shows the geometry of O2 molecule. Both Cartesian and internal coordinates are supported.

Computational Results

In this case, totally 10 VB structures are generated. The number of 0th ion structure is 6, and the number of 1th ion structures is 4. These structures can be expaned into 16 determinants.

Number of   0th ion  structures  is:          6  from          1 to          6
Number of   0th ion determinants is:         12  from          1 to         12
Number of   1th ion  structures  is:          4  from          7 to         10
Number of   1th ion determinants is:          4  from         13 to         16
Total number of  structures  is:         10
Total number of determinants is:         16

Number of Structures:          10
                   .
                   .
                   .
The following structures are used in calculation:

    1 *****  1:5    6   6   7   7   8   9
    2 *****  1:5    6   6   8   8   7   9
    3 *****  1:5    6   6   9   9   7   8
    4 *****  1:5    7   7   8   8   6   9
    5 *****  1:5    7   7   9   9   6   8
    6 *****  1:5    8   8   9   9   6   7
    7 *****  1:5    6   6   7   7   8   8
    8 *****  1:5    6   6   7   7   9   9
    9 *****  1:5    6   6   8   8   9   9
   10 *****  1:5    7   7   8   8   9   9

Note

In this (6,4) active space, there are at least 2 active orbitals are always doubly occupied. For instnce, in structure “1:5 6 6 7 7 8 9”, the active orbitals 6 and 7 are doubly occupied, and the electrons on orbitals 8 and 9 form a covalent bond. However, this structure belongs to “0th ion structure” instead of “2th ion structure”.

The user may find from the output file that the VBSCF converged after 43 iterations and the final energy is -149.59869269 hartree.

                       VBSCF converged in    43 iterations

Total Energy:    -149.59869269

First Excited:   -149.598693

The coefficients and weights shows the importance of each structure. Following are the coefficients and weights of generated VB structures. Both coefficients and weights show that structures 1 and 6 are dominant. Structure 1 means the covalent bodning between py orbitals of the two O atoms, while Structure 6 means the covalent bodning between px orbitals of the two O atoms

    ******  COEFFICIENTS OF STRUCTURES ******

 1       0.59132818  *****  1:5    6   6   7   7   8   9
 2      -0.00000000  *****  1:5    6   6   8   8   7   9
 3       0.00000000  *****  1:5    6   6   9   9   7   8
 4       0.00000000  *****  1:5    7   7   8   8   6   9
 5       0.00000000  *****  1:5    7   7   9   9   6   8
 6      -0.59163406  *****  1:5    8   8   9   9   6   7
 7       0.14679997  *****  1:5    6   6   7   7   8   8
 8       0.14680176  *****  1:5    6   6   7   7   9   9
 9      -0.14686415  *****  1:5    6   6   8   8   9   9
10      -0.14686585  *****  1:5    7   7   8   8   9   9
               .
               .
               .
    ******  WEIGHTS OF STRUCTURES ******

 1       0.40213218  *****  1:5    6   6   7   7   8   9
 2       0.00000000  *****  1:5    6   6   8   8   7   9
 3       0.00000000  *****  1:5    6   6   9   9   7   8
 4       0.00000000  *****  1:5    7   7   8   8   6   9
 5      -0.00000000  *****  1:5    7   7   9   9   6   8
 6       0.40253540  *****  1:5    8   8   9   9   6   7
 7       0.04881265  *****  1:5    6   6   7   7   8   8
 8       0.04881349  *****  1:5    6   6   7   7   9   9
 9       0.04885274  *****  1:5    6   6   8   8   9   9
10       0.04885354  *****  1:5    7   7   8   8   9   9

Finally, the bond order value (1.347) in atomic population analysis shows that O-O bond should be a double bond.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 O           2 O            1.227       1.347

Computations of the triplet state

The geometry, basis set and active space are the same as the singlet calculation in the previuos section.

Input File

Here shows the XMVB input file for all the structures

triplet O2 VBSCF with all structures
$CTRL
STR=FULL NAO=4 NAE=6 IPRINT=3
ORBTYP=HAO FRGTYP=SAO
BASIS=CC-PVDZ NMUL=3
GUESS=READ
$END
$FRAG
1*6
SPZDXXDYYDZZ 1
SPZDXXDYYDZZ 2
PXDXZ 1
PXDXZ 2
PYDYZ 1
PYDYZ 2
$END
$ORB
1*4 2 1*4
1
2
1
2
1 2
3
4
5
6
$END
$GEO
O 0.0 0.0 0.0
O 0.0 0.0 1.227
$END
$GUS
     8     8     8     8    16     3     3     3     3
# ORBITAL          1  NAO =       8
-1.0001816769     1  -0.0219071559     2  -0.0208718204     3   0.0055675373     6
 0.0058885238     9   0.0012121651    10   0.0012098650    13   0.0014914363    15
# ORBITAL          2  NAO =       8
-1.0001807197    16  -0.0219222377    17  -0.0208875165    18  -0.0055748376    21
-0.0058896710    24   0.0012101317    25   0.0012115362    28   0.0014916466    30
# ORBITAL          3  NAO =       8
-0.0380292983     1   0.4956131485     2   0.5430800220     3  -0.1721288256     6
-0.1265645521     9   0.0040244173    10   0.0040243680    13  -0.0013604634    15
# ORBITAL          4  NAO =       8
-0.0380587693    16   0.4956124042    17   0.5430787036    18   0.1721299458    21
 0.1265653159    24   0.0040244421    25   0.0040243828    28  -0.0013600709    30
# ORBITAL          5  NAO =      16
-0.1873055284     1  -0.0320312577     2   0.1037620245     3  -0.7575342039     6
-0.1745797408     9   0.0069166781    10   0.0069169372    13  -0.0385887223    15
-0.1873136771    16  -0.0320328992    17   0.1037594786    18   0.7575341385    21
 0.1745797704    24   0.0069172963    25   0.0069171279    28  -0.0385889746    30
# ORBITAL          6  NAO =       3
 0.6907525874     4   0.4550551271     7   0.0256096827    12
# ORBITAL          7  NAO =       3
 0.6907525665    19   0.4550551519    22  -0.0256096585    27
# ORBITAL          8  NAO =       3
 0.6907525875     5   0.4550551269     8   0.0256096869    14
# ORBITAL          9  NAO =       3
 0.6907525683    20   0.4550551500    23  -0.0256096533    29
$END

The only difference of this input file from that in the previuos section is that the spin multiplicity is set to 3 for the triplet state.

  • NMUL=3 The spin multiplicity (2S+1) is 3.

Computational Results

In this case, totally 6 VB structures (or 6 VB determinants) are generated, and all of them are 0th ion structures.

Number of   0th ion  structures  is:          6  from          1 to          6
Number of   0th ion determinants is:          6  from          1 to          6
Total number of  structures  is:          6
Total number of determinants is:          6

Number of Structures:           6
                   .
                   .
                   .
The following structures are used in calculation:

    1 *****  1:5    6   6   7   7   8   9
    2 *****  1:5    6   6   8   8   7   9
    3 *****  1:5    6   6   9   9   7   8
    4 *****  1:5    7   7   8   8   6   9
    5 *****  1:5    7   7   9   9   6   8
    6 *****  1:5    8   8   9   9   6   7

Note

In this (6,4) active space, there are at least 2 active orbitals are always doubly occupied. Different from the calculation of singlet state, the remaining 2 electrons are in the same spin. Since two electrons with same spin cannot occupy on one spatial orbital, there is no “1th ion structures” in this case.

Note

For a structure with \(2S+1\neq1\), the last \(2S\) numbers means unpaired electrons with same spin instaed of covalent boinding in the singlet case. For instance, structure “1:5 6 6 7 7 8 9” in this triplet calculation means there are two unpaired electrons with same spin on orbitals 8 and 9.

The user may find from the output file that the VBSCF converged after 43 iterations and the final energy is -149.62744434 hartree.

                       VBSCF converged in    43 iterations

Total Energy:    -149.62744434

First Excited:   -149.440051

Note

Compared with the energy of singlet state (-149.59869269 hartree), we see the VB theroy correctly predict the ground state as triplet!

The coefficients and weights shows the importance of each structure. Following are the coefficients and weights of generated VB structures. Both coefficients and weights show that structures 3 and 4 are mainly dominant. Structure 3 means there are two unpaired electrons with same spin on px orbital of O2 and py orbital of O1. Structure 4 means there are two unpaired electrons with same spin on px orbital of O1 and py orbital of O2. The structures 2 and 5 also give nonneglegible contributions, but are less important than structures 3 and 4. This is because both structures 2 and 5 means there are two unpaired electrons with same spin on one O atom.

   ******  COEFFICIENTS OF STRUCTURES ******

1      -0.00000000  *****  1:5    6   6   7   7   8   9
2       0.24299537  *****  1:5    6   6   8   8   7   9
3      -0.55305281  *****  1:5    6   6   9   9   7   8
4      -0.55305265  *****  1:5    7   7   8   8   6   9
5       0.24299211  *****  1:5    7   7   9   9   6   8
6       0.00000000  *****  1:5    8   8   9   9   6   7
              .
              .
              .
   ******  WEIGHTS OF STRUCTURES ******

1       0.00000000  *****  1:5    6   6   7   7   8   9
2       0.12068238  *****  1:5    6   6   8   8   7   9
3       0.37931891  *****  1:5    6   6   9   9   7   8
4       0.37931871  *****  1:5    7   7   8   8   6   9
5       0.12068001  *****  1:5    7   7   9   9   6   8
6       0.00000000  *****  1:5    8   8   9   9   6   7

Finally, the bond order value (1.779) in atomic population analysis shows that the triplet O2 is more stable than the singlet whose bond order is 1.347.

          ******  BOND ORDER  ******

ATOM 1        ATOM 2           DIST     BOND ORDER

 1 O           2 O            1.227       1.779

Computations with selected structures

In the previous calculations of O2, the structures in the VB wave function are all automatically generated (STR=FULL). However, it’s possible to perform a VB calculation with selected structures. The structures can be selected by either chemical intuition or a previous VB calculation. Followings are input files of singlet and triplet O2 with selected structures.

Input File

Here shows the XMVB input file with selected structures for both singlet and triplet O2.

singlet O2 VBSCF with selected structures
$CTRL
NSTR=2 NAO=4 NAE=6 IPRINT=3
ORBTYP=HAO FRGTYP=SAO
BASIS=CC-PVDZ NMUL=1
GUESS=READ
$END
$FRAG
1*6
SPZDXXDYYDZZ 1
SPZDXXDYYDZZ 2
PXDXZ 1
PXDXZ 2
PYDYZ 1
PYDYZ 2
$END
$ORB
1*4 2 1*4
1
2
1
2
1 2
3
4
5
6
$END
$STR
1:5    6   6   7   7   8   9
1:5    8   8   9   9   6   7
$END
$GEO
O 0.0 0.0 0.0
O 0.0 0.0 1.227
$END
$GUS
     8     8     8     8    16     3     3     3     3
# ORBITAL          1  NAO =       8
-1.0001816769     1  -0.0219071559     2  -0.0208718204     3   0.0055675373     6
 0.0058885238     9   0.0012121651    10   0.0012098650    13   0.0014914363    15
# ORBITAL          2  NAO =       8
-1.0001807197    16  -0.0219222377    17  -0.0208875165    18  -0.0055748376    21
-0.0058896710    24   0.0012101317    25   0.0012115362    28   0.0014916466    30
# ORBITAL          3  NAO =       8
-0.0380292983     1   0.4956131485     2   0.5430800220     3  -0.1721288256     6
-0.1265645521     9   0.0040244173    10   0.0040243680    13  -0.0013604634    15
# ORBITAL          4  NAO =       8
-0.0380587693    16   0.4956124042    17   0.5430787036    18   0.1721299458    21
 0.1265653159    24   0.0040244421    25   0.0040243828    28  -0.0013600709    30
# ORBITAL          5  NAO =      16
-0.1873055284     1  -0.0320312577     2   0.1037620245     3  -0.7575342039     6
-0.1745797408     9   0.0069166781    10   0.0069169372    13  -0.0385887223    15
-0.1873136771    16  -0.0320328992    17   0.1037594786    18   0.7575341385    21
 0.1745797704    24   0.0069172963    25   0.0069171279    28  -0.0385889746    30
# ORBITAL          6  NAO =       3
 0.6907525874     4   0.4550551271     7   0.0256096827    12
# ORBITAL          7  NAO =       3
 0.6907525665    19   0.4550551519    22  -0.0256096585    27
# ORBITAL          8  NAO =       3
 0.6907525875     5   0.4550551269     8   0.0256096869    14
# ORBITAL          9  NAO =       3
 0.6907525683    20   0.4550551500    23  -0.0256096533    29
$END

“NSTR=2” means 2 structures are involved in the VB wave function. When “NSTR=value” is specified in the input, the “$STR” section, which describes the details of the selected structures, must be provided.

triplet O2 VBSCF with selected structures
$CTRL
NSTR=2 NAO=4 NAE=6 IPRINT=3
ORBTYP=HAO FRGTYP=SAO
BASIS=CC-PVDZ NMUL=3
GUESS=READ
$END
$FRAG
1*6
SPZDXXDYYDZZ 1
SPZDXXDYYDZZ 2
PXDXZ 1
PXDXZ 2
PYDYZ 1
PYDYZ 2
$END
$ORB
1*4 2 1*4
1
2
1
2
1 2
3
4
5
6
$END
$STR
1:5    6   6   9   9   7   8
1:5    7   7   8   8   6   9
$END
$GEO
O 0.0 0.0 0.0
O 0.0 0.0 1.227
$END
$GUS
     8     8     8     8    16     3     3     3     3
# ORBITAL          1  NAO =       8
-1.0001816769     1  -0.0219071559     2  -0.0208718204     3   0.0055675373     6
 0.0058885238     9   0.0012121651    10   0.0012098650    13   0.0014914363    15
# ORBITAL          2  NAO =       8
-1.0001807197    16  -0.0219222377    17  -0.0208875165    18  -0.0055748376    21
-0.0058896710    24   0.0012101317    25   0.0012115362    28   0.0014916466    30
# ORBITAL          3  NAO =       8
-0.0380292983     1   0.4956131485     2   0.5430800220     3  -0.1721288256     6
-0.1265645521     9   0.0040244173    10   0.0040243680    13  -0.0013604634    15
# ORBITAL          4  NAO =       8
-0.0380587693    16   0.4956124042    17   0.5430787036    18   0.1721299458    21
 0.1265653159    24   0.0040244421    25   0.0040243828    28  -0.0013600709    30
# ORBITAL          5  NAO =      16
-0.1873055284     1  -0.0320312577     2   0.1037620245     3  -0.7575342039     6
-0.1745797408     9   0.0069166781    10   0.0069169372    13  -0.0385887223    15
-0.1873136771    16  -0.0320328992    17   0.1037594786    18   0.7575341385    21
 0.1745797704    24   0.0069172963    25   0.0069171279    28  -0.0385889746    30
# ORBITAL          6  NAO =       3
 0.6907525874     4   0.4550551271     7   0.0256096827    12
# ORBITAL          7  NAO =       3
 0.6907525665    19   0.4550551519    22  -0.0256096585    27
# ORBITAL          8  NAO =       3
 0.6907525875     5   0.4550551269     8   0.0256096869    14
# ORBITAL          9  NAO =       3
 0.6907525683    20   0.4550551500    23  -0.0256096533    29
$END

Computational Results

The VBSCF calculations with selected structure for singlet and triplet O2 are respectivlely -149.54466456 and -149.55699157 hartree. It’s not surprising the energies with selected structures are higher than those with all structures in the actve space. The calculations with selected structures again correctly predict the ground state of O2 as triplet.

Readers can further check and compared other quantities in the output files.

VB Exercises: Advanced Part

Slides

Slides for Advanced Exercises

Slides for advanded exercises can be downloaded here.

Computing of post-VBSCF methods

Introduction

The multiconfiguration nature of VBSCF method enables VB theory to successfully describe the complicated electronic structure in strongly correlated systems. The wave function of a strongly correlated system is dominated by more than one configuration state function (CSF) or VB structure. The electronic correlation due to this degeneracy is known as static correlation. On the other hand, a more accurate description of strongly correlated systems also requires the inclusion of dynamic correlation. The dynamic correlation could be introduced by using post-SCF methods, such as perturbation theory (PT), configuration interaction (CI), coupled-cluster (CC), or density functional theory (DFT), etc. Therefore, more precise and advanced VB methods have been proposed to involve both static and dynamic correlations. The commonly used post-VBSCF methods include breathing-orbital valence bond (BOVB), valence bond configuration interaction (VBCI), valence bond perturbation theory (VBPT2), and density functional valence bond (DFVB).

The BOVB is a classical VB method which mimics a ‘breathing’ effect by allowing the orbitals to be different in different structures. For H2 molecule, the VBSCF wave function is

\[\Psi^{VBSCF}=C_1(|\phi_a\overline{\phi}_b|-|\overline{\phi}_a\phi_b|))+C_2|\phi_a\overline{\phi}_a|+C_3|\phi_b\overline{\phi}_b|\]

while the BOVB wave function is written as

\[\Psi^{BOVB}=C_1(|\phi_a\overline{\phi}_b|-|\overline{\phi}_a\phi_b|))+C_2|\phi^{'}_a\overline{\phi^{'}}_a|+C_3|\phi^{'}_b\overline{\phi^{'}}_b|\]

Therefore, BOVB method gives lower energies compared with VBSCF by introducing dynamic correlation with extra degrees of freedom of the orbital coefficients. There are various levels of BOVB, including L-BOVB, D-BOVB, SL-BOVB, and SD-BOVB. In L-BOVB, all orbitals are strictly localized (HAOs), while OEOS are used in D-BOVB. “S” in SL-BOVB and SD-BOVB stands for splitting the doubly occupied orbitals for ionic bond.

The VBCI is the most precise (though also the most expensive) classical VB method. In VBCI method, all the occupied orbitals are required to be HAOs so that the strictly localized virtual orbitals are constructed by using a projector localized on one atom or fragment. Then the CI procedure is perfomred by allowing the electron excitation from the occupied otbials to virtual ones whithin each atom or fragment.

The BOVB and VBCI are classical post-VBSCF methods, and the wave functions are constructed by HAOs. In VBPT2, however, the virtual orbitals are orthogonal by allowing the delocalization over the whole molecule. Therefore, the excited VB structures in VBPT2 are not limited to local excitation. This means the chemical pictures of excited VB structures are less clear than those in VBCI, but the computational cost of VBPT2 is much lower than VBCI.

Kohn-Sham DFT is widely applied in electronic structure calculations, due to its cheap computational cost for dynamic correlation. Various DFVB methods which combine KS-DFT and VBSCF have been proposed to efficiently include dynamic correlation in VBSCF wave function. In the dynamic correlated DFVB (dc-DFVB) method, the DFT correlation is straightforward added to the VBSCF energy. In the Hamiltonian corrected DFVB (hc-DFVB) method, the DFT correlation is added to each Hamiltonian matrix element. In a series of hybrid DFVB (λ-DFVB) methods, the electron-electron interaction is divided into the wave function and DFT parts with a hybrid parameter λ, which is related to the multiconfiguration character of the studied molecule.

In this section, three post-VBSCF methods (BOVB, VBPT2 and hc-DFVB) are applied to the computing of resonance energy of F2 molecule. All the computations are proceeded with F-F bond length 1.4 Angstrom, and the basis set is cc-pVDZ. For simplicity, F atoms are located in the Z axis.

Computing with BOVB method

Input File

 F2 BOVB calculation with 3 structures
 $CTRL
 STR=FULL NAO=2 NAE=2 IPRINT=3 BOVB
 ORBTYP=HAO FRGTYP=SAO
 BASIS=CC-PVDZ GUESS=READ
 $END
 $FRAG
 1*6
 SPZDXXDYYDZZ 1
 SPZDXXDYYDZZ 2
 PXDXZ 1
 PXDXZ 2
 PYDYZ 1
 PYDYZ 2
 $END
 $ORB
 1*10
 1
 2
 1
 2
 3
 4
 5
 6
 1
 2
 $END
 $GEO
 F 0.0 0.0 0.0
 F 0.0 0.0 1.4
 $END
 $VEC
 8   8   8   8   3   3   3   3   8   8
 # ORBITAL        1  NAO =     8
 1.0008523635   1  -0.0002451908   2  -0.0033475855   3   0.0007822794   6
-0.0004308019   9  -0.0009672775  10  -0.0009672547  11  -0.0015047199  12
 # ORBITAL        2  NAO =     8
 1.0008523652  16  -0.0002450266  17  -0.0033475641  18  -0.0007832238  21
 0.0004299611  24  -0.0009663380  25  -0.0009641029  26  -0.0015084314  27
 # ORBITAL        3  NAO =     8
-0.0046583295   1  -0.5140815122   2  -0.5639080344   3   0.0635587135   6
 0.0463521927   9  -0.0000387922  10  -0.0000387928  11   0.0006078983  12
 # ORBITAL        4  NAO =     8
-0.0046580393  16  -0.5140815112  17  -0.5639080329  18  -0.0635586939  21
-0.0463521769  24  -0.0000388134  25  -0.0000388635  26   0.0006079803  27
 # ORBITAL        5  NAO =     3
 0.6920248541   4   0.4582846681   7   0.0074447939  14
 # ORBITAL        6  NAO =     3
 0.6920248517  19   0.4582846708  22  -0.0074447974  29
 # ORBITAL        7  NAO =     3
 0.6920248541   5   0.4582846681   8   0.0074447939  15
 # ORBITAL        8  NAO =     3
 0.6920248499  20   0.4582846729  23  -0.0074447973  30
 # ORBITAL        9  NAO =     8
 0.0453208934   1  -0.0554693805   2   0.0178207146   3  -0.7191076297   6
-0.4212641367   9   0.0105222178  10   0.0105222177  11  -0.0469454207  12
 # ORBITAL       10  NAO =     8
 0.0453208934  16  -0.0554693808  17   0.0178207148  18   0.7191076300  21
 0.4212641368  24   0.0105222168  25   0.0105222108  26  -0.0469454121  27
 $END

Readers can compare this input file with that of VBSCF. In the BOVB calculation, the “BOVB” keyword is specified. The “GUESS=READ” keyword means the orbital guess is taken from the $VEC (can be also written as “$GUS”) section. The optimal orbitals can be found in the file with “.orb” extension after a calculation is done.

Note

In post-VBSCF calculation, it’s always recommended to provide the optimal VBSCF orbitals as initial guess.

Computational Results

In this case, 3 VB structures are generated with 1 covalent structure (0th ion structure) and 2 ionic structures (1th ion structures). These structures can be expaned into 4 determinants.

Number of   0th ion  structures  is:          1  from          1 to          1
Number of   0th ion determinants is:          2  from          1 to          2
Number of   1th ion  structures  is:          2  from          2 to          3
Number of   1th ion determinants is:          2  from          3 to          4
Total number of  structures  is:          3
Total number of determinants is:          4

Breathing Orbitals
Structure   2:   1 ->  11
                 2 ->  12
                 3 ->  13
                 4 ->  14
                 5 ->  15
                 6 ->  16
                 7 ->  17
                 8 ->  18
                 9 ->  19
Structure   3:   1 ->  20
                 2 ->  21
                 3 ->  22
                 4 ->  23
                 5 ->  24
                 6 ->  25
                 7 ->  26
                 8 ->  27
                10 ->  28
                   .
                   .
                   .
Number of Structures:           3

The following structures are used in calculation:
      1 *****     1   1   2   2   3   3   4   4   5   5   6   6   7   7   8   8   9  10
      2 *****    11  11  12  12  13  13  14  14  15  15  16  16  17  17  18  18  19  19
      3 *****    20  20  21  21  22  22  23  23  24  24  25  25  26  26  27  27  28  28

Since the orbitals in each structure are different in BOVB wave function, the orbitals in structure 1 are labeled as 1-10 (the same as those given by the user). In structure 2, which corresponds to the ionic structure “1:8 9 9” in VBSCF, the 9 orbitals are labeled as 11-19. In structure 3, which corresponds to the ionic structure “1:8 10 10” in VBSCF, the 9 orbitals are labeled as 20-28.

The user may find from the output file that the final BOVB energy is -198.78317897 hartree, which is lower than the VBSCF energy (-198.75115493 hartree) due to the inclusion of dynamic correlation in BOVB.

Following are the coefficients and weights of generated VB structures. Both coefficients and weights show that the covalent structure is also the dominant one in BOVB calculation. Readers can find the BOVB weight of the covalent structure (0.70862656) is smaller than VBSCF (0.77586). This phenomenon can often be found in post-VBSCF calculations since the structures with higher energies in VBSCF gain more correlation in post-VBSCF methods.

       ******  COEFFICIENTS OF STRUCTURES ******

1      -0.75348845  ******     1   1   2   2   3   3   4   4   5   5   6   6   7   7   8   8   9  10
2      -0.26504301  ******    11  11  12  12  13  13  14  14  15  15  16  16  17  17  18  18  19  19
3      -0.26504287  ******    20  20  21  21  22  22  23  23  24  24  25  25  26  26  27  27  28  28
                  .
                  .
                  .
       ******  WEIGHTS OF STRUCTURES ******

1       0.70862656  ******     1   1   2   2   3   3   4   4   5   5   6   6   7   7   8   8   9  10
2       0.14568688  ******    11  11  12  12  13  13  14  14  15  15  16  16  17  17  18  18  19  19
3       0.14568656  ******    20  20  21  21  22  22  23  23  24  24  25  25  26  26  27  27  28  28

Computing with VBPT2 method

Input File

 F2 VBPT2 calculation with 3 structures
 $CTRL
 STR=FULL NAO=2 NAE=2 IPRINT=3 VBPT2
 ORBTYP=HAO FRGTYP=SAO
 BASIS=CC-PVDZ GUESS=READ
 $END
 $FRAG
 1*6
 SPZDXXDYYDZZ 1
 SPZDXXDYYDZZ 2
 PXDXZ 1
 PXDXZ 2
 PYDYZ 1
 PYDYZ 2
 $END
 $ORB
 1*10
 1
 2
 1
 2
 3
 4
 5
 6
 1
 2
 $END
 $GEO
 F 0.0 0.0 0.0
 F 0.0 0.0 1.4
 $END
 $VEC
 8   8   8   8   3   3   3   3   8   8
 # ORBITAL        1  NAO =     8
 1.0008523635   1  -0.0002451908   2  -0.0033475855   3   0.0007822794   6
-0.0004308019   9  -0.0009672775  10  -0.0009672547  11  -0.0015047199  12
 # ORBITAL        2  NAO =     8
 1.0008523652  16  -0.0002450266  17  -0.0033475641  18  -0.0007832238  21
 0.0004299611  24  -0.0009663380  25  -0.0009641029  26  -0.0015084314  27
 # ORBITAL        3  NAO =     8
-0.0046583295   1  -0.5140815122   2  -0.5639080344   3   0.0635587135   6
 0.0463521927   9  -0.0000387922  10  -0.0000387928  11   0.0006078983  12
 # ORBITAL        4  NAO =     8
-0.0046580393  16  -0.5140815112  17  -0.5639080329  18  -0.0635586939  21
-0.0463521769  24  -0.0000388134  25  -0.0000388635  26   0.0006079803  27
 # ORBITAL        5  NAO =     3
 0.6920248541   4   0.4582846681   7   0.0074447939  14
 # ORBITAL        6  NAO =     3
 0.6920248517  19   0.4582846708  22  -0.0074447974  29
 # ORBITAL        7  NAO =     3
 0.6920248541   5   0.4582846681   8   0.0074447939  15
 # ORBITAL        8  NAO =     3
 0.6920248499  20   0.4582846729  23  -0.0074447973  30
 # ORBITAL        9  NAO =     8
 0.0453208934   1  -0.0554693805   2   0.0178207146   3  -0.7191076297   6
-0.4212641367   9   0.0105222178  10   0.0105222177  11  -0.0469454207  12
 # ORBITAL       10  NAO =     8
 0.0453208934  16  -0.0554693808  17   0.0178207148  18   0.7191076300  21
 0.4212641368  24   0.0105222168  25   0.0105222108  26  -0.0469454121  27
 $END

Readers can compare this input file with that of VBSCF. In the VBPT2 calculation, the “VBPT2” keyword is specified. The orbital guess is taken from the $VEC section.

Computational Results

In VBPT2 calculation, the reference is the VBSCF wav function, and therefore aslo includes 3 structures or 4 determinants.

The user may find from the output file that the final VBPT2 energy is -199.09559220 hartree.

Note

Since the virtual orbitals in VBPT2 are delocazlied, the chemical pictures of exciteted structures are less clear than those in VBCI, and the structural weights are not computed in VBPT2.

Computing with hc-DFVB method

Input File

 F2 hc-DFVB calculation with 3 structures
 $CTRL
 STR=FULL NAO=2 NAE=2 IPRINT=3 HC-DFVB=B3LYP
 ORBTYP=HAO FRGTYP=SAO
 BASIS=CC-PVDZ GUESS=READ
 $END
 $FRAG
 1*6
 SPZDXXDYYDZZ 1
 SPZDXXDYYDZZ 2
 PXDXZ 1
 PXDXZ 2
 PYDYZ 1
 PYDYZ 2
 $END
 $ORB
 1*10
 1
 2
 1
 2
 3
 4
 5
 6
 1
 2
 $END
 $GEO
 F 0.0 0.0 0.0
 F 0.0 0.0 1.4
 $END
 $VEC
 8   8   8   8   3   3   3   3   8   8
 # ORBITAL        1  NAO =     8
 1.0008523635   1  -0.0002451908   2  -0.0033475855   3   0.0007822794   6
-0.0004308019   9  -0.0009672775  10  -0.0009672547  11  -0.0015047199  12
 # ORBITAL        2  NAO =     8
 1.0008523652  16  -0.0002450266  17  -0.0033475641  18  -0.0007832238  21
 0.0004299611  24  -0.0009663380  25  -0.0009641029  26  -0.0015084314  27
 # ORBITAL        3  NAO =     8
-0.0046583295   1  -0.5140815122   2  -0.5639080344   3   0.0635587135   6
 0.0463521927   9  -0.0000387922  10  -0.0000387928  11   0.0006078983  12
 # ORBITAL        4  NAO =     8
-0.0046580393  16  -0.5140815112  17  -0.5639080329  18  -0.0635586939  21
-0.0463521769  24  -0.0000388134  25  -0.0000388635  26   0.0006079803  27
 # ORBITAL        5  NAO =     3
 0.6920248541   4   0.4582846681   7   0.0074447939  14
 # ORBITAL        6  NAO =     3
 0.6920248517  19   0.4582846708  22  -0.0074447974  29
 # ORBITAL        7  NAO =     3
 0.6920248541   5   0.4582846681   8   0.0074447939  15
 # ORBITAL        8  NAO =     3
 0.6920248499  20   0.4582846729  23  -0.0074447973  30
 # ORBITAL        9  NAO =     8
 0.0453208934   1  -0.0554693805   2   0.0178207146   3  -0.7191076297   6
-0.4212641367   9   0.0105222178  10   0.0105222177  11  -0.0469454207  12
 # ORBITAL       10  NAO =     8
 0.0453208934  16  -0.0554693808  17   0.0178207148  18   0.7191076300  21
 0.4212641368  24   0.0105222168  25   0.0105222108  26  -0.0469454121  27
 $END

Readers can compare this input file with that of VBSCF, and find that the only difference is the “HC-DFVB=B3LYP” keyword is specified. This keyword is specified for a hc-DFVB calculation, and B3LYP functional is used in this case. Currently, the program supports only LDA, GGA and their hybrid functionals; meta-GGA and corresponding hybrid functional are not avaiable temporaily.

Computational Results

In hc-DFVB calculation, the reference is the VBSCF wave function, and therefore aslo includes 3 structures or 4 determinants.

The user may find from the output file that the final hc-DFVB energy is -199.40139652 hartree. The hc-DFVB correlation energy (-0.65024078 hartree) is also printed out.

Readers can find in the output file the “MATRIX OF EC HAMILTONIAN FOR HC-DFVB”, which is a correlation correction matrix in the structure basis. In this case, it reads as

   ******  MATRIX OF EC HAMILTONIAN FOR HC-DFVB ******

           1            2            3
1      -0.647844    -0.240498    -0.240498
2      -0.240498    -0.658429    -0.047883
3      -0.240498    -0.047883    -0.658429

It can be found that the correlation energy of the covalent structure is -0.647844 hartree, which is smaller (in absolute value) than that of ionic structure (-0.658429 hartree). This phenomenon, which is also found in the previous BOVB calculation, again shows that structures with higher energies in VBSCF gain more correlation in post-VBSCF methods.

Computing of diabatic states with VB theory

Introduction

Molecular dynamical process involving excited states is usually simulated under the Born-Oppenheimer adiabatic approximation, in which the adiabatic electronic states are used to construct the potential energy surfaces (PESs). Adiabatic states are eigenstates of electronic Hamiltonian, and thus unique for a given quantum chemical method. For instance, the eigenstates obtained by solving the generalized secular equation \(\textbf{HC}=\textbf{MCE}\) in VBSCF are adiabatic states. In nonadiabatic dynamics, to solve the quantum equation of motion requires the evaluation of nuclear-momentum couplings (NMCs) \(\textbf{F}_{KL}\)

\[F_{KL} = \langle \Psi_K \left( \mathbf{r;R} \right) \vert \nabla_R \vert \Psi_L\left( \mathbf{r;R} \right) \rangle\]

where \(\Psi_K(\textbf{r};\textbf{R})\) is the electronic wave function of state K with parametrical dependence on the nuclear coordinates \(\textbf{R}\). Specially, \(\textbf{F}_{KL}\) in adiabatic state basis is called nonadiabatic couplings (NACs). The complexity arises near the conical intersections where the NACs have singularities due to the rapid change of the character of the adiabatic wave function. The sudden change of the adiabatic wave function can be understood according to the following figure, which could be interpreted as a conical intersection between one covalent state and one ionic state. Suppose that the adiabatic state \(\Psi_1\) is mainly covalent and \(\Psi_2\) is mainly ionic before the avoided crossing point (\(R^c\)). Then singularity of \(\textbf{F}_{12}\) occurs at \(R^c\) when \(\Psi_1\) rapidly changes to ionic and \(\Psi_2\) rapidly changes to covalent. It is possible to remove such singularity by constructing the PESs with diabatic states. In diabatic state basis, the electronic Hamiltonian is not diagonal, and the effect of the NMCs should be negligible compared with the off-diagonal elements of the electronic Hamiltonian. Therefore, the definition of diabatic states is not unique.

_images/lif_2.jpg

Illustration of adiabatic states (solid lines) and diabatic states (dashed lines).

Various schemes based on molecular orbital theory have been proposed to construct the diabatic states. On the contrary, the construction of diabatic states with VB theory seems more straightforward, since each VB structure exactly corresponds to a Lewis structure, and thus never changes its character along the PES. In this section, two ways to construct diabtic states with VB theory are presented for LiF molecule.

LiF is a simple hetero diatomic molecule with a single bond between atoms Li and F. The dissociation of LiF is always in the interest of chemists. The so-called “Harpoon effect” makes electron transfer when the distance between Li and F even larger than the sum of their van der Waals radius, indicating an electron transfer due to the crossing of diabatic states. For details, please refer to the reference.

In this exercise, users will compute a series of points along the dissociation of LiF for the first two electronic states, get the energies of both the adiabatic and diabatic states with VB theory, and plot the potential energy surface. The basis set in this exercise is cc-pVDZ, and the active space is the minimal (2,2) space, which includes the \(2s\) orbital of Li atom and \(2p_z\) orbital of F atom.

Computations of adiabatic states

The distance RLi-F is 1.5 Å in the example input file below.

Input file

 The first two adiabatic states of LiF
 $CTRL
 STR=FULL NAO=2 NAE=2 IPRINT=3
 ORBTYP=HAO FRGTYP=SAO
 BASIS=CC-PVDZ
 WSTATE(1)=0.5,0.5 GUESS=READ
 $END
 $FRAG
 1*4
 SPZDXXDYYDZZ 1
 SPZDXXDYYDZZ 2
 PXDXZ 2
 PYDYZ 2
 $END
 $ORB
 1*7
 1
 2
 2
 3
 4
 1
 2
 $END
 $GEO
 Li 0.0 0.0 0.0
 F  0.0 0.0 1.5
 $END
 $VEC
 8   8   8   3   3   8   8
 # ORBITAL        1  NAO =     8
 1.0006124741   1   0.0010947827   2  -0.0001697524   3  -0.0054823903   6
 0.0022720913   9  -0.0024855501  10  -0.0024855494  11  -0.0029391815  12
 # ORBITAL        2  NAO =     8
-0.9878720649  16   0.0820885570  17   0.1032423966  18  -0.0041896343  21
-0.0056696719  24   0.0001113470  25   0.0001115264  26   0.0012300179  27
 # ORBITAL        3  NAO =     8
 0.1608417532  16   0.4836528017  17   0.5898820135  18  -0.0253431901  21
-0.0323439728  24  -0.0057810288  25  -0.0057799058  26  -0.0006485649  27
 # ORBITAL        4  NAO =     3
-0.6610782115  19  -0.4931501640  22   0.0078682530  29
 # ORBITAL        5  NAO =     3
-0.6610781961  20  -0.4931501514  23   0.0078713335  30
 # ORBITAL        6  NAO =     8
-0.0485005246   1   0.3835061386   2   0.5812431299   3  -0.3104635019   6
-0.0450765604   9   0.0269723639  10   0.0269723820  11  -0.0250362698  12
 # ORBITAL        7  NAO =     8
-0.0016023849  16  -0.0212026440  17   0.0287929283  18  -0.6406201457  21
-0.5152310378  24  -0.0077601696  25  -0.0077603299  26   0.0077058038  27
 $END

Note

  • There is only a single bond in the molecule, so the minimal active space should be (2,2).

  • VB structures can be automatically generated as we have seen in the example of F2.

  • Use keywords ORBTYP=HAO and FRGTYP=SAO with proper definition of fragmenets in $FRAG to build the orbitals.

  • The active orbitals should always be placed at the last in $ORB section.

  • Orbitals obtained in previous computation can be used as initial guess.

The keyword “WSTATE(1)=0.5,0.5” in the $CTRL section is specified for the state-averaged VBSCF calulation. The state-averaged scheme is needed for the calculation of excited states in multiconfigurational methods. In state-averaged scheme, the wave function for each electronic state is optimized variationally to minimize the averaged energy (E) of interested N states as

\[E=\sum_{i=1}^{N}w_iE_i\]

where \(E_i\) is the energy of state i, and \(w_i\) is the corresponding weight in the averaged scheme. In most cases, the electronc states are averaged with same weights. In the “WSTATE(K)= \(w_1,w_2,...\)" keyword, the averaged scheme is described as following: the Kth state is averaged with weight w1, the \((K+1)\)th state is averaged with weight w2, and so on. In this case, the first two electronic states are averaged, and the weight of the first state (ground state) is 0.5, and the weight of the second state (first excited state) is also 0.5.

The “GUESS=READ” keyword means the orbital guess is taken from the $VEC section. For a calculation of potential energy curve, the orbital guess is often chosen as the optimal orbitals of the molecuar geometry nearby. The optimal orbitals can be found in the file with “.orb” extension after a calculation is done.

Computation of diabatic states with chemical insights

For LiF molecule, the definition of the first two diabatic states is straightforward, i.e. the covalent structure Li-F and the ionic structure Li+ F-. The input files for the calculations of the two diabatic states are shown below.

 The covalent diabatic state of LiF
 $CTRL
 NSTR=1 NAO=2 NAE=2 IPRINT=3
 ORBTYP=HAO FRGTYP=SAO GUESS=READ
 BASIS=CC-PVDZ
 $END
 $FRAG
 1*4
 SPZDXXDYYDZZ 1
 SPZDXXDYYDZZ 2
 PXDXZ 2
 PYDYZ 2
 $END
 $ORB
 1*7
 1
 2
 2
 3
 4
 1
 2
 $END
 $STR
 1:5 6 7
 $END
 $GEO
 Li 0.0 0.0 0.0
 F  0.0 0.0 1.5
 $END
 $VEC
 8     8     8     3     3     8     8
 # ORBITAL          1  NAO =       8
-1.0011678861     1  -0.0022121270     2   0.0023212935     3  -0.0025335037     6
 0.0016875131     9   0.0025270489    10   0.0023274646    13   0.0026480262    15
 # ORBITAL          2  NAO =       8
-1.0008168299    16   0.0036845277    17   0.0071487300    18  -0.0001661450    21
-0.0003147690    24   0.0010390175    25   0.0010419561    28   0.0015319075    30
 # ORBITAL          3  NAO =       8
-0.0101097268    16  -0.5128227302    17  -0.5703498101    18   0.0266052512    21
 0.0288144250    24   0.0021878838    25   0.0021691970    28  -0.0016764977    30
 # ORBITAL          4  NAO =       3
 0.6907944105    19   0.4597105881    22  -0.0059097276    27
 # ORBITAL          5  NAO =       3
 0.6907940010    20   0.4597105227    23  -0.0059816036    29
 # ORBITAL          6  NAO =       8
-0.0238842027     1  -0.4984202033     2  -0.5284694265     3   0.2687769028     6
 0.1065714103     9  -0.0107075041    10  -0.0107111179    13   0.0798765082    15
 # ORBITAL          7  NAO =       8
 0.0080197261    16  -0.0318421895    17  -0.0744506221    18   0.7073285005    21
 0.4345585123    24   0.0040544825    25   0.0040620001    28  -0.0046080448    30
 $END
 The ionic diabatic state of LiF
 $CTRL
 NSTR=1 NAO=2 NAE=2 IPRINT=3
 ORBTYP=HAO FRGTYP=SAO GUESS=READ
 BASIS=CC-PVDZ
 $END
 $FRAG
 1*4
 SPZDXXDYYDZZ 1
 SPZDXXDYYDZZ 2
 PXDXZ 2
 PYDYZ 2
 $END
 $ORB
 1*7
 1
 2
 2
 3
 4
 1
 2
 $END
 $STR
 1:5 7 7
 $END
 $GEO
 Li 0.0 0.0 0.0
 F  0.0 0.0 1.5
 $END
 $VEC
 8     8     8     3     3     8     8
 # ORBITAL          1  NAO =       8
-1.0004203054     1   0.0002038534     2   0.0005481657     3   0.0132303641     6
-0.0065003814     9   0.0021658077    10   0.0021658077    13   0.0027685384    15
 # ORBITAL          2  NAO =       8
-1.0008305986    16  -0.0017058286    17   0.0010077161    18   0.0003735826    21
-0.0001046315    24   0.0011858422    25   0.0011849757    28   0.0011520210    30
 # ORBITAL          3  NAO =       8
 0.0205934347    16  -0.4655906963    17  -0.6286682097    18   0.0355102258    21
 0.0460224079    24   0.0093958692    25   0.0093958715    28   0.0024192082    30
 # ORBITAL          4  NAO =       3
 0.6265556203    19   0.5304582609    22  -0.0098651162    27
 # ORBITAL          5  NAO =       3
 0.6265556195    20   0.5304582617    23  -0.0098651162    29
 # ORBITAL          6  NAO =       8
-0.1494486185     1  -0.7392177847     2   0.2171735656     3  -0.7734875826     6
 0.2332816045     9   0.3272572338    10   0.3272572338    13  -0.5469570507    15
 # ORBITAL          7  NAO =       8
 0.0096938330    16   0.0583635389    17   0.0122710208    18   0.6211959886    21
 0.5329337539    24   0.0088600826    25   0.0088600766    28  -0.0093045652    30
 $END

For the covalent diabatic state Li-F, the corrsponding structure is “1:5 6 7”; For the ionic diabatic state Li+ F-, the corrsponding structure is “1:5 7 7”. From the output files, readers can find the energy of the covalent structure is -106.74408537 hartree, and the energy of the ionic structure is -106.89954237 hartree. Therefore, the bonding of Li-F is dominated by the ionic structure near equilibrium geometry. After bond dissociation, however, the bonding of Li-F is dominated by the covalent structure. The potential energy curves of these two diabatic states are plotted in the following figure.

_images/lif_3.jpg

The potential energy curves of two diabatic states obtained by chmical insights.

Note

Careful readers may notice the potential energy curves of VBSCF adiabatic states are not consistent with those in reference. This is because VBSCF is not accurate enough, and better curves can be obtained with post-VBSCF methods.

Computation of diabatic states with VBCAD

Instead of diabatization scheme with chemical insights, the valence-bond-based compression approach for diabatization (VBCAD), however, is a black-box-like diabatization scheme. In VBCAD, the electronic Hamiltonian is first compressed into a low dimensional matrix Hpre-dia containing only the interested electronic states, and then the diabatic Hamiltonian (Hdia) is obtained by a transformation to Hpre-dia. The transformation is determined by maximizing the separation of VB structures in different electronic states. For more details, please refer to reference.

An example input file for VBCAD calculation is shown below

 The first two diabatic states of LiF with VBCAD
 $CTRL
 STR=FULL NAO=2 NAE=2 IPRINT=3
 ORBTYP=HAO FRGTYP=SAO
 BASIS=CC-PVDZ
 WSTATE(1)=0.5,0.5 GUESS=READ VBCAD
 $END
 $FRAG
 1*4
 SPZDXXDYYDZZ 1
 SPZDXXDYYDZZ 2
 PXDXZ 2
 PYDYZ 2
 $END
 $ORB
 1*7
 1
 2
 2
 3
 4
 1
 2
 $END
 $GEO
 Li 0.0 0.0 0.0
 F  0.0 0.0 1.5
 $END
 $VEC
 8   8   8   3   3   8   8
 # ORBITAL        1  NAO =     8
 1.0006124741   1   0.0010947827   2  -0.0001697524   3  -0.0054823903   6
 0.0022720913   9  -0.0024855501  10  -0.0024855494  11  -0.0029391815  12
 # ORBITAL        2  NAO =     8
-0.9878720649  16   0.0820885570  17   0.1032423966  18  -0.0041896343  21
-0.0056696719  24   0.0001113470  25   0.0001115264  26   0.0012300179  27
 # ORBITAL        3  NAO =     8
 0.1608417532  16   0.4836528017  17   0.5898820135  18  -0.0253431901  21
-0.0323439728  24  -0.0057810288  25  -0.0057799058  26  -0.0006485649  27
 # ORBITAL        4  NAO =     3
-0.6610782115  19  -0.4931501640  22   0.0078682530  29
 # ORBITAL        5  NAO =     3
-0.6610781961  20  -0.4931501514  23   0.0078713335  30
 # ORBITAL        6  NAO =     8
-0.0485005246   1   0.3835061386   2   0.5812431299   3  -0.3104635019   6
-0.0450765604   9   0.0269723639  10   0.0269723820  11  -0.0250362698  12
 # ORBITAL        7  NAO =     8
-0.0016023849  16  -0.0212026440  17   0.0287929283  18  -0.6406201457  21
-0.5152310378  24  -0.0077601696  25  -0.0077603299  26   0.0077058038  27
 $END

The keyword “VBCAD” is specified for a black-box-like diabatization with VB theory. Currently, VBCAD supports diabatization with only 2 electronic states.

In the output file, the Hamiltonian in the diabatic state basis is printed out as

       ******  Diabatic Hamiltonian ******

           1            2
1    -106.714613     0.013448
2       0.013448  -106.877770

followed by the printing of energy and wave function of each diabatic state.

       VBCAD DIABATIC STATE:     1
       VBCAD DIABATIC ENERGY:    -106.714613


       ******  COEFFICIENTS OF STRUCTURES ******

1     1.00169  ******  1:5    6   7
2    -0.01716  ******  1:5    6   6
3    -0.02505  ******  1:5    7   7

  CC Weights

1     1.00123  ******  1:5    6   7
2    -0.00058  ******  1:5    6   6
3    -0.00065  ******  1:5    7   7
               .
               .
               .
       VBCAD DIABATIC STATE:     2
       VBCAD DIABATIC ENERGY:    -106.877770


       ******  COEFFICIENTS OF STRUCTURES ******

1     0.02599  ******  1:5    6   7
2     0.00044  ******  1:5    6   6
3    -1.00099  ******  1:5    7   7

  CC Weights

1    -0.00065  ******  1:5    6   7
2     0.00000  ******  1:5    6   6
3     1.00065  ******  1:5    7   7

It can be found from the CC weights section, the covalent structure Li-F dominats the ground diabatic state, while the ionic structure Li+ F- dominats the first excited diabatic state. This is in consistent with the fact that near equilibrium Li-F bond length, the ground diabatic state is described as covalent, and the first excited diabatic state is described as ionic.

The potential energy curves of these two VBCAD states together with the adiabatic states are plotted in the following figure.

_images/lif_4.jpg

The potential energy curves of the VBCAD states together with the adiabatic states.

Menshutkin Reaction NH3 + CH3Cl \(\rightarrow\) [NH3CH3]+ + Cl-

Chemical question to be addressed

This exercise is the Menshutkin reaction NH3 + CH3Cl \(\rightarrow\) [NH3CH3]+ + Cl-. The reaction is exothermic in solution. In this example, the reaction barrier in gas phase will be calculated with L-VBSCF and L-BOVB. For more information of the reaction and the computations in solution, please refer to:

  1. Su, P.; Ying, F.; Wu, W.; Hiberty, P. C.; Shaik, S. The Menshutkin Reaction in the Gas Phase and in Aqueous Solution: A Valence Bond Study. ChemPhysChem 2007, 8 (18), 2603–2614.

  2. Shaik, S.; Danovich, D.; Joy, J.; Hiberty, P. C. Valence Bond Diagrams and Chemical Reactivity. In Reference Module in Chemistry, Molecular Sciences and Chemical Engineering; Elsevier, 2022.

Active/inactive electrons and orbitals

The reaction involves the breaking of the CH3-Cl bond and building of an NH3-CH3 bond. As such, the lone pair on NH3 and the CH3-Cl bond in the reactants constitute the active space, which involves 4 electrons on 3 orbitals. The remaining 32 electrons and 16 orbitals constitute the inactive space, including the core orbitals of N, C and Cl, 3 N-H bonds, 3 C-H bonds, and 3 s, 3 px and 3 py orbitals on Cl.

Fragmentation and important VB structures

The reaction involves 3 fragments: NH3, CH3 and Cl. The reactants include non-interacting NH3 and CH3Cl moieties while the product includes non-interacting [NH3CH3]+ and Cl- moieties. Following figure shows the important VB structures in reactant (a) and product (b).

_images/menshutkin-geo.jpg
_images/menshutkin-scheme13.jpg

Lewis structure for the reactant (a) and product (b).

Basis set and its subsets based on orbital symmetry

6–31G* is the basis set used in this example. The basis functions are simply separated into subsets according to the atoms. The basis functions on each atom will be treated as a subset and the VB orbitals will be built with these subsets.

Structures

There are 6 VB structures involved in the active space as shown in the figure. Structures S1-S3 describe the reactant, and S3-S5 describe the product. S6 describes the electron transfer between NH3 and Cl, and will appear in the TS region.

_images/menshutkin-scheme14.jpg

6 VB structures for Menshutkin Reaction.

Input File

The input files of L-VBSCF for reactant and TS are given below:

Reactant:

NH3CH3cl reactant
$ctrl
nmul=1 nstr=6 iprint=3 nao=3 nae=4
orbtyp=hao frgtyp=atom
basis=6-31G*
guess=read
$end
$stru
1:16 17 17 18 19
1:16 17 17 18 18
1:16 17 17 19 19
1:16 18 18 17 19
1:16 19 19 17 18
1:16 18 18 19 19
$end
$orb
1*5 4 4 1*3 4*3 4*3 4 4 1
6
6
6
6
6
1 7 8 9
2 3 4 5
6
6
6
1 7 8 9
1 7 8 9
1 7 8 9
2 3 4 5
2 3 4 5
2 3 4 5
1 7 8 9
2 3 4 5
6
$end
$geo
 N      0.000000    0.000000    0.000000
 C      0.000000    0.000000   10.000000
 H     -1.029985    0.000000    9.647297
 H      0.514992    0.891993    9.647297
 H      0.514992   -0.891993    9.647297
 Cl     0.000000    0.000000   11.778400
 H      0.939678    0.000000   -0.389227
 H     -0.469839    0.813785   -0.389227
 H     -0.469839   -0.813785   -0.389227
$end

TS:

NH3CH3cl
$ctrl
nmul=1 nstr=6 iprint=3 nao=3 nae=4 itmax=300
guess=read orbtyp=hao frgtyp=atom
basis=6-31G*
$end
$stru
1:16 17 17 18 19
1:16 17 17 18 18
1:16 17 17 19 19
1:16 18 18 17 19
1:16 19 19 17 18
1:16 18 18 19 19
$end
$orb
1*5 4 4 1*3 4*3 4*3 4 4 1
6
6
6
6
6
1 7 8 9
2 3 4 5
6
6
6
1 7 8 9
1 7 8 9
1 7 8 9
2 3 4 5
2 3 4 5
2 3 4 5
1 7 8 9
2 3 4 5
6
$end
$geo
N    0.0000000000   0.0000000000  -2.4403680000
C    0.0000000000   0.0000000000  -0.6327610000
H    1.0651490000   0.0000000000  -0.4753840000
H   -0.5325745000  -0.9224460928  -0.4753840000
H   -0.5325745000   0.9224460928  -0.4753840000
CL   0.0000000000   0.0000000000   1.8067450000
H   -0.9550790000   0.0000000000  -2.8031240000
H    0.4775395000   0.8271226766  -2.8031240000
H    0.4775395000  -0.8271226766  -2.8031240000
$end

The input files are almost the same except the initial guess and geometry. The initial guess of reactant is given here. The initial guess of TS can be obtained from the computational results of reactant. For L-BOVB computations, the user may simply append BOVB in $CTRL section. The initial guess of L-BOVB computations are from the computational results of correpsonding L-VBSCF computation.

Computational Results

The VB structures

Following table shows the VB structures involved in the calculation. The first 16 doubly occupied orbitals are inactive ones, orbital 17 corresponds to the lone pair on NH3, and orbitals 18 and 19 are singly occupied orbitals on CH3 and Cl respectively. The correspondence to the structures is also listed.

Table VB structures involved in Menshutkin reaction

VB structure

Structure

1 ***** 1:16 17 17 18 19

S1

2 ***** 1:16 17 17 18 18

S2

3 ***** 1:16 17 17 19 19

S3

4 ***** 1:16 18 18 17 19

S6

5 ***** 1:16 19 19 17 18

S4

6 ***** 1:16 18 18 19 19

S5

Energies

Following table shows the total energies (in a.u.) and reaction barrier at the L-VBSCF and L-BOVB levels. Compared with the reference value 33.0 kcal mol -1 (138.1 kJ mol -1) by Webb and Gordon, L-VBSCF overestimates the reaction barrier due to the lack of dynamic correlation, and L-BOVB significantly improves the result. Compared with the energies obtained by L-VBSCF and L-BOVB, L-BOVB decreases the energy at the TS geometry much more than in the reactants. The results show that dynamic correlation plays an important role in reaction barrier calculations.

Total energies (in a.u.) and reaction barrier \(\Delta E^\neq\) (in kcal/mol) by L-VBSCF and L-BOVB

L-VBSCF

L-BOVB

\(E^{react}_{tot}\)

-555.27775

-555.29156

\(E^{TS}_{tot}\)

-555.21152

-555.24558

\(\Delta E^\neq\)

41.6

28.8

VB wavefunction and weights

Table shows the weights of VB structures in the reactant and TS geometries. It is clear that the most important contribution comes from S1 in the reactant geometry and S3 in the TS geometry. In the TS, S4 represents the “covalent” structure of product and S3 represents the major “ionic” structure in both reactant and product. Thus, S3 represents the “bond breaking” of C-Cl and S4 shows the “bond forming” of N-C. Similar to the previous examples, L-BOVB provides larger weights for the secondary ionic structures as compared with L-VBSCF weights, which indicates that dynamic correlation plays a more important role for structures with higher VBSCF energies, as already explained.

Coulson-Chirgwin weights of VB structures in reactant and TS geometries with L-VBSCF and L-BOVB

Reactant

TS

L-VBSCF

L-BOVB

L-VBSCF

L-BOVB

S1

0.663

0.621

0.091

0.178

S2

0.105

0.120

-0.001

0.002

S3

0.232

0.259

0.532

0.487

S4

0.000

0.000

0.364

0.286

S5

0.000

0.000

-0.004

0.010

S6

0.000

0.000

0.017

0.037

Charge-shift bonding in propellane

Introduction

In this section, the charge-shift bonding nature of the C-C bridge bond (shown in the following figue) in the [1.1.1]propellane compound (propellane for short in this section) is investigated. As mentioned in Section 3.2.1, the charge-shift bond is identified if the resonance energy of the bond exceeds 50% of the bonding energy.

_images/propellane.jpg

The structure of the propellane compound.

The computations are proceeded with the given geometry in the following input files, and the basis set is cc-pVDZ. The calulation is at BOVB level.

Computations of the resonance energy

propellane BOVB calculation with 3 structures
$CTRL
STR=FULL NAO=2 NAE=2 IPRINT=3 BOVB
ORBTYP=HAO GUESS=READ
BASIS=CC-PVDZ
$END

$ORB
1*5 2*12 1*2
1    # 1  C1     1s
2    # 2  C2     1s
3    # 3  C3     1s
4    # 4  C4     1s
5    # 5  C5     1s
1 3  # 6  C1-C3  sigma
2 3  # 7  C2-C3  sigma
1 4  # 8  C1-C4  sigma
2 4  # 9  C2-C4  sigma
1 5  # 10 C1-C5  sigma
2 5  # 11 C2-C5  sigma
3 6  # 12 C3-H6  sigma
3 7  # 13 C3-H7  sigma
4 8  # 14 C4-H8  sigma
4 9  # 15 C4-H9  sigma
5 10 # 16 C5-H10 sigma
5 11 # 17 C5-H11 sigma

1    # 18 C1-C2  sigma C1
2    # 19 C1-C2  sigma C2
$END

$GEO
 C              -0.80339320     -0.00000002     -0.00026581
 C               0.80339315      0.00000002     -0.00026580
 C              -0.00000000      0.00000000      1.30328491
 C               0.00000001      1.12889613     -0.65192077
 C              -0.00000002     -1.12889613     -0.65192076
 H               0.00000002      0.90072681      1.88197724
 H               0.00000001     -0.90072681      1.88197723
 H              -0.00000001      2.07996500     -0.16030252
 H               0.00000003      1.18070087     -1.72126710
 H               0.00000001     -1.18070087     -1.72126709
 H               0.00000000     -2.07996501     -0.16030253
$END

$VEC
    15    15    15    15    15    30    30    30    30    30    30    20    20    20    20    20    20    15    15
# ORBITAL          1  NAO =      15
 1.0013044300     1  -0.0148185006     2  -0.0270614351     3   0.0014157398     4
-0.0000001541     5   0.0000015008     6  -0.0017992610     7  -0.0000067568     8
-0.0000032993     9  -0.0008838473    10  -0.0000009796    11   0.0000002515    12
-0.0015986173    13   0.0000013752    14  -0.0016010424    15
# ORBITAL          2  NAO =      15
 1.0013053868    16  -0.0148178712    17  -0.0270673561    18  -0.0014157125    19
-0.0000002118    20   0.0000016740    21   0.0018009244    22  -0.0000010308    23
 0.0000054004    24  -0.0008824051    25  -0.0000002306    26  -0.0000009051    27
-0.0015985372    28   0.0000006106    29  -0.0015993992    30
# ORBITAL          3  NAO =      15
 0.9991206001    31  -0.0171860691    32  -0.0162161271    33   0.0000007618    34
 0.0000013055    35  -0.0006957167    36  -0.0000014569    37   0.0000001571    38
 0.0000790563    39  -0.0020670891    40  -0.0000011719    41   0.0000010731    42
-0.0021065954    43  -0.0000022108    44  -0.0023469285    45
# ORBITAL          4  NAO =      15
 0.9991202122    46  -0.0171853822    47  -0.0162125157    48   0.0000006933    49
-0.0005994343    50   0.0003494060    51  -0.0000008239    52   0.0000652009    53
-0.0000372870    54  -0.0020683845    55  -0.0000009837    56  -0.0000004101    57
-0.0022864381    58   0.0001199393    59  -0.0021660489    60
# ORBITAL          5  NAO =      15
 0.9991212097    61  -0.0171850657    62  -0.0162182626    63   0.0000004025    64
 0.0006008934    65   0.0003484130    66   0.0000035522    67  -0.0000702075    68
-0.0000394260    69  -0.0020683512    70   0.0000006972    71   0.0000002999    72
-0.0022870879    73  -0.0001190917    74  -0.0021658981    75
# ORBITAL          6  NAO =      30
-0.0177774926     1  -0.2162705930     2  -0.2298798504     3   0.0706361562     4
 0.0000024378     5  -0.3238519858     6   0.0667063348     7  -0.0000256996     8
-0.1556546218     9   0.0097518542    10  -0.0000027624    11  -0.0301554752    12
 0.0092026397    13  -0.0000002305    14  -0.0263744821    15  -0.0147709460    31
-0.1460413984    32  -0.1155006162    33   0.2650092251    34   0.0000006955    35
 0.1839524192    36   0.1404511764    37   0.0000407801    38   0.0925295733    39
-0.0107900693    40   0.0000018292    41  -0.0282003496    42   0.0136549918    43
 0.0000054096    44  -0.0097832753    45
# ORBITAL          7  NAO =      30
-0.0177658023    16  -0.2162486406    17  -0.2299525549    18  -0.0706350937    19
-0.0000014106    20  -0.3238462405    21  -0.0666827544    22  -0.0000053780    23
-0.1555802125    24   0.0097646308    25  -0.0000018502    26   0.0301631205    27
 0.0092087511    28   0.0000029753    29  -0.0263731317    30  -0.0147687986    31
-0.1460413510    32  -0.1155156453    33  -0.2649967418    34  -0.0000072210    35
 0.1839401239    36  -0.1405170026    37  -0.0000348214    38   0.0924884616    39
-0.0107989165    40  -0.0000016736    41   0.0282085984    42   0.0136617248    43
-0.0000053124    44  -0.0097795494    45
# ORBITAL          8  NAO =      30
-0.0177577308     1  -0.2162013994     2  -0.2299673947     3   0.0706110630     4
-0.2804620260     5   0.1619371044     6   0.0666333857     7  -0.1348756187     8
 0.0778258361     9   0.0097734916    10  -0.0261267575    11   0.0150869471    12
-0.0174618406    13   0.0178097102    14   0.0003162100    15  -0.0147732236    46
-0.1460578616    47  -0.1155220923    48   0.2650144529    49   0.1592704233    50
-0.0920250702    51   0.1404068731    52   0.0800667609    53  -0.0462473103    54
-0.0107879126    55  -0.0244083850    56   0.0141015632    57  -0.0039034180    58
 0.0117339554    59   0.0077884189    60
# ORBITAL          9  NAO =      30
 0.0177761911    16   0.2162548982    17   0.2298552881    18   0.0706285957    19
 0.2805096055    20  -0.1619483728    21   0.0667282475    22   0.1348077090    23
-0.0778328435    24  -0.0097796081    25  -0.0261254688    26   0.0150935495    27
 0.0174656722    28  -0.0178011546    29  -0.0003043329    30   0.0147931236    46
 0.1461082080    47   0.1153584115    48   0.2650336900    49  -0.1592773444    50
 0.0920130590    51   0.1405345297    52  -0.0800770669    53   0.0462541047    54
 0.0108069299    55  -0.0244257552    56   0.0141067392    57   0.0039234196    58
-0.0117232129    59  -0.0077872362    60
# ORBITAL         10  NAO =      30
 0.0177805057     1   0.2162405637     2   0.2298076785     3  -0.0706044220     4
-0.2804965339     5  -0.1619531390     6  -0.0666833559     7  -0.1347393815     8
-0.0777019246     9  -0.0097445984    10  -0.0261176194    11  -0.0150718170    12
 0.0174729106    13   0.0177945974    14  -0.0002864287    15   0.0147874057    61
 0.1460888402    62   0.1154517089    63  -0.2650232945    64   0.1592757818    65
 0.0920142609    66  -0.1405860261    67   0.0801337784    68   0.0462885854    69
 0.0108070870    70  -0.0244331942    71  -0.0141107441    72   0.0039410936    73
 0.0117131673    74  -0.0078047684    75
# ORBITAL         11  NAO =      30
 0.0177799561    16   0.2162227894    17   0.2298148247    18   0.0705868963    19
-0.2804588970    20  -0.1619115261    21   0.0666441698    22  -0.1348267513    23
-0.0778975430    24  -0.0097385288    25   0.0261260325    26   0.0150938317    27
 0.0174863028    28   0.0178098786    29  -0.0003106634    30   0.0147619518    61
 0.1460362911    62   0.1156613683    63   0.2650100271    64   0.1592697337    65
 0.0920215396    66   0.1403723237    67   0.0801289455    68   0.0462892649    69
 0.0107835415    70   0.0244067802    71   0.0140992591    72   0.0039118995    73
 0.0117295466    74  -0.0077996863    75
# ORBITAL         12  NAO =      20
 0.0172973458    31   0.2021529787    32   0.1246606235    33  -0.0000031809    34
 0.3042972540    35   0.1970108564    36   0.0000068028    37   0.1300804271    38
 0.0908986389    39  -0.0079455903    40   0.0000048018    41  -0.0000039238    42
 0.0117793218    43   0.0139996205    44  -0.0073463152    45   0.4270402124    76
 0.1295468232    77  -0.0000053093    78  -0.0294631198    79  -0.0195166579    80
# ORBITAL         13  NAO =      20
-0.0173282009    31  -0.2022108198    32  -0.1243909531    33  -0.0000096109    34
 0.3043243458    35  -0.1970216211    36  -0.0000042424    37   0.1300749867    38
-0.0909331248    39   0.0079484887    40  -0.0000056809    41   0.0000028882    42
-0.0117996319    43   0.0139959547    44   0.0073369181    45  -0.4270900640    81
-0.1296000887    82   0.0000006580    83  -0.0294618950    84   0.0195172636    85
# ORBITAL         14  NAO =      20
 0.0173002408    46   0.2021118790    47   0.1246240723    48   0.0000022713    49
 0.3227889720    50   0.1649529052    51  -0.0000148620    52   0.1438492365    53
 0.0672219489    54  -0.0079367406    55   0.0000175697    56  -0.0000089690    57
 0.0079591066    58   0.0165643938    59  -0.0034869406    60   0.4270093758    86
 0.1295884488    87   0.0000016180    88  -0.0316194875    89  -0.0157531870    90
# ORBITAL         15  NAO =      20
-0.0173086687    46  -0.2021939367    47  -0.1245611168    48   0.0000003610    49
-0.0183875471    50   0.3620460821    51   0.0000673331    52  -0.0136415635    53
 0.1580963305    54   0.0079527536    55  -0.0000113874    56   0.0000032002    57
 0.0130569871    58  -0.0025806853    59  -0.0175049037    60  -0.4270744827    91
-0.1295400125    92   0.0000001650    93   0.0021637053    94  -0.0352738044    95
# ORBITAL         16  NAO =      20
-0.0173183346    61  -0.2022026360    62  -0.1245109940    63   0.0000075545    64
 0.0183988865    65   0.3620424314    66  -0.0000395096    67   0.0136658395    68
 0.1581128420    69   0.0079480868    70  -0.0000049906    71  -0.0000080201    72
 0.0130454991    73   0.0025855278    74  -0.0175242163    75  -0.4270686231    96
-0.1295457954    97  -0.0000005864    98  -0.0021655869    99  -0.0352696895   100
# ORBITAL         17  NAO =      20
 0.0173197873    61   0.2021511454    62   0.1244587778    63  -0.0000011094    64
-0.3228115619    65   0.1649560698    66   0.0000052783    67  -0.1438497907    68
 0.0671949240    69  -0.0079405965    70   0.0000104455    71  -0.0000034930    72
 0.0079482684    73  -0.0165642389    74  -0.0034671716    75   0.4270459111   101
 0.1296314976   102  -0.0000009897   103   0.0316266447   104  -0.0157561697   105
# ORBITAL         18  NAO =      15
-0.0163776922     1  -0.0583204663     2   0.1324850019     3  -0.6739726665     4
-0.0000444708     5  -0.0000310706     6  -0.4551573242     7  -0.0000875557     8
-0.0000314392     9  -0.0756705415    10  -0.0000033820    11  -0.0000057832    12
 0.0323892303    13   0.0000190463    14   0.0323603700    15
# ORBITAL         19  NAO =      15
-0.0163754625    16  -0.0583193461    17   0.1324498525    18   0.6739423059    19
 0.0000015891    20  -0.0000003256    21   0.4551921058    22  -0.0000787438    23
-0.0000153122    24  -0.0756649095    25   0.0000030203    26  -0.0000219594    27
 0.0323852880    28  -0.0000064669    29   0.0323956416    30
$END

Careful readers may wonder why the $FRAG section is missing in this input file. This is because, each atom is defined as a fragment in default, if $FRAG section is not specified by the user. In the default case, atom 1 is defined as fragment 1, atom 2 is defined as fragment 2, and so on. The description of each orbital in the calculation is shown in the $ORB section. In the input file, the contents after “#” in a line is regarded as comments, and will not be read by the program. The “GUESS=READ” keyword is specified for the BOVB calculation, and the VBSCF optimal orbitals are provided as initial guess in the $VEC section.

To obtain the resonance energy, another input file to comput the energy with one covalent structure is needed. The BOVB energy of the total 3 structures is -192.68236940 hartree, and that of one covalent structure is -192.58034082 hartree. Therefore, the resonance enenrgy of the C-C bridge bond is 64.02 kcal/mol at BOVB level.

Note

Careful readers may notice the BOVB energy with one covalent structure is exactly identical to the VBSCF enenrgy. This is because BOVB includes dynamic corrlation by allowing different orbitals in different structures. When the wave funtion contains only one structure, the BOVB and VBSCF wave functions are identical.

Computations of the bonding energy

The bodning energy is the energy difference between the equilibrium geometry and the geometry after bond breaking. In the previous F2 moleucle, the bond breaking geometry is simply described by setting the F-F distance as a large value (10 Å for instance). In this propellane case, however, it’s impossible to stretch the C-C bridge bond while keeping the molecular skeleton.

To approximately estimated the bonding energy of the C-C bridge bond, we define a quasiclassical (QC) state as a reference non-bonded state. For a single bond, the bonded state is the covalent state \(\Phi^{cov}=\frac{1}{\sqrt{2+2s_{ab}}}(|\phi_a\overline{\phi}_b|-|\overline{\phi}_a\phi_b|)\), and the QC state can be either \(|\phi_a\overline{\phi}_b|\) or \(|\overline{\phi}_a\phi_b|\). Each of these determinants has only quasi-classical interactions between the two fragments and is therefore non-bonding, while the covalent bonding arises from the interaction of the two determinants that give rise to the singlet-coupled covalent state \(\Phi^{cov}\). This covalent bond energy, complemented by the resonance energy stabilization due to the mixing of the ionic structures into the covalent structure measures the “in-situ” bonding energy. As such, the “in-situ” bonidng energy, which is the energy difference between the QC state and state with totally 3 structures provides an approximated measure of the C-C bridge boning energy.

The following is a input file to compuete the QC state.

QC state calculation of propellane
$CTRL
WFNTYP=DET NSTR=1 NAO=2 NAE=2 IPRINT=3
ORBTYP=HAO GUESS=READ
BASIS=CC-PVDZ
$END
$STR
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 19
$END
$ORB
1*5 2*12 1*2
1    # 1  C1     1s
2    # 2  C2     1s
3    # 3  C3     1s
4    # 4  C4     1s
5    # 5  C5     1s
1 3  # 6  C1-C3  sigma
2 3  # 7  C2-C3  sigma
1 4  # 8  C1-C4  sigma
2 4  # 9  C2-C4  sigma
1 5  # 10 C1-C5  sigma
2 5  # 11 C2-C5  sigma
3 6  # 12 C3-H6  sigma
3 7  # 13 C3-H7  sigma
4 8  # 14 C4-H8  sigma
4 9  # 15 C4-H9  sigma
5 10 # 16 C5-H10 sigma
5 11 # 17 C5-H11 sigma

1    # 18 C1-C2  sigma C1
2    # 19 C1-C2  sigma C2
$END

$GEO
 C              -0.80339320     -0.00000002     -0.00026581
 C               0.80339315      0.00000002     -0.00026580
 C              -0.00000000      0.00000000      1.30328491
 C               0.00000001      1.12889613     -0.65192077
 C              -0.00000002     -1.12889613     -0.65192076
 H               0.00000002      0.90072681      1.88197724
 H               0.00000001     -0.90072681      1.88197723
 H              -0.00000001      2.07996500     -0.16030252
 H               0.00000003      1.18070087     -1.72126710
 H               0.00000001     -1.18070087     -1.72126709
 H               0.00000000     -2.07996501     -0.16030253
$END

$VEC
    15    15    15    15    15    30    30    30    30    30    30    20    20    20    20    20    20    15    15
# ORBITAL          1  NAO =      15
 1.0013044300     1  -0.0148185006     2  -0.0270614351     3   0.0014157398     4
-0.0000001541     5   0.0000015008     6  -0.0017992610     7  -0.0000067568     8
-0.0000032993     9  -0.0008838473    10  -0.0000009796    11   0.0000002515    12
-0.0015986173    13   0.0000013752    14  -0.0016010424    15
# ORBITAL          2  NAO =      15
 1.0013053868    16  -0.0148178712    17  -0.0270673561    18  -0.0014157125    19
-0.0000002118    20   0.0000016740    21   0.0018009244    22  -0.0000010308    23
 0.0000054004    24  -0.0008824051    25  -0.0000002306    26  -0.0000009051    27
-0.0015985372    28   0.0000006106    29  -0.0015993992    30
# ORBITAL          3  NAO =      15
 0.9991206001    31  -0.0171860691    32  -0.0162161271    33   0.0000007618    34
 0.0000013055    35  -0.0006957167    36  -0.0000014569    37   0.0000001571    38
 0.0000790563    39  -0.0020670891    40  -0.0000011719    41   0.0000010731    42
-0.0021065954    43  -0.0000022108    44  -0.0023469285    45
# ORBITAL          4  NAO =      15
 0.9991202122    46  -0.0171853822    47  -0.0162125157    48   0.0000006933    49
-0.0005994343    50   0.0003494060    51  -0.0000008239    52   0.0000652009    53
-0.0000372870    54  -0.0020683845    55  -0.0000009837    56  -0.0000004101    57
-0.0022864381    58   0.0001199393    59  -0.0021660489    60
# ORBITAL          5  NAO =      15
 0.9991212097    61  -0.0171850657    62  -0.0162182626    63   0.0000004025    64
 0.0006008934    65   0.0003484130    66   0.0000035522    67  -0.0000702075    68
-0.0000394260    69  -0.0020683512    70   0.0000006972    71   0.0000002999    72
-0.0022870879    73  -0.0001190917    74  -0.0021658981    75
# ORBITAL          6  NAO =      30
-0.0177774926     1  -0.2162705930     2  -0.2298798504     3   0.0706361562     4
 0.0000024378     5  -0.3238519858     6   0.0667063348     7  -0.0000256996     8
-0.1556546218     9   0.0097518542    10  -0.0000027624    11  -0.0301554752    12
 0.0092026397    13  -0.0000002305    14  -0.0263744821    15  -0.0147709460    31
-0.1460413984    32  -0.1155006162    33   0.2650092251    34   0.0000006955    35
 0.1839524192    36   0.1404511764    37   0.0000407801    38   0.0925295733    39
-0.0107900693    40   0.0000018292    41  -0.0282003496    42   0.0136549918    43
 0.0000054096    44  -0.0097832753    45
# ORBITAL          7  NAO =      30
-0.0177658023    16  -0.2162486406    17  -0.2299525549    18  -0.0706350937    19
-0.0000014106    20  -0.3238462405    21  -0.0666827544    22  -0.0000053780    23
-0.1555802125    24   0.0097646308    25  -0.0000018502    26   0.0301631205    27
 0.0092087511    28   0.0000029753    29  -0.0263731317    30  -0.0147687986    31
-0.1460413510    32  -0.1155156453    33  -0.2649967418    34  -0.0000072210    35
 0.1839401239    36  -0.1405170026    37  -0.0000348214    38   0.0924884616    39
-0.0107989165    40  -0.0000016736    41   0.0282085984    42   0.0136617248    43
-0.0000053124    44  -0.0097795494    45
# ORBITAL          8  NAO =      30
-0.0177577308     1  -0.2162013994     2  -0.2299673947     3   0.0706110630     4
-0.2804620260     5   0.1619371044     6   0.0666333857     7  -0.1348756187     8
 0.0778258361     9   0.0097734916    10  -0.0261267575    11   0.0150869471    12
-0.0174618406    13   0.0178097102    14   0.0003162100    15  -0.0147732236    46
-0.1460578616    47  -0.1155220923    48   0.2650144529    49   0.1592704233    50
-0.0920250702    51   0.1404068731    52   0.0800667609    53  -0.0462473103    54
-0.0107879126    55  -0.0244083850    56   0.0141015632    57  -0.0039034180    58
 0.0117339554    59   0.0077884189    60
# ORBITAL          9  NAO =      30
 0.0177761911    16   0.2162548982    17   0.2298552881    18   0.0706285957    19
 0.2805096055    20  -0.1619483728    21   0.0667282475    22   0.1348077090    23
-0.0778328435    24  -0.0097796081    25  -0.0261254688    26   0.0150935495    27
 0.0174656722    28  -0.0178011546    29  -0.0003043329    30   0.0147931236    46
 0.1461082080    47   0.1153584115    48   0.2650336900    49  -0.1592773444    50
 0.0920130590    51   0.1405345297    52  -0.0800770669    53   0.0462541047    54
 0.0108069299    55  -0.0244257552    56   0.0141067392    57   0.0039234196    58
-0.0117232129    59  -0.0077872362    60
# ORBITAL         10  NAO =      30
 0.0177805057     1   0.2162405637     2   0.2298076785     3  -0.0706044220     4
-0.2804965339     5  -0.1619531390     6  -0.0666833559     7  -0.1347393815     8
-0.0777019246     9  -0.0097445984    10  -0.0261176194    11  -0.0150718170    12
 0.0174729106    13   0.0177945974    14  -0.0002864287    15   0.0147874057    61
 0.1460888402    62   0.1154517089    63  -0.2650232945    64   0.1592757818    65
 0.0920142609    66  -0.1405860261    67   0.0801337784    68   0.0462885854    69
 0.0108070870    70  -0.0244331942    71  -0.0141107441    72   0.0039410936    73
 0.0117131673    74  -0.0078047684    75
# ORBITAL         11  NAO =      30
 0.0177799561    16   0.2162227894    17   0.2298148247    18   0.0705868963    19
-0.2804588970    20  -0.1619115261    21   0.0666441698    22  -0.1348267513    23
-0.0778975430    24  -0.0097385288    25   0.0261260325    26   0.0150938317    27
 0.0174863028    28   0.0178098786    29  -0.0003106634    30   0.0147619518    61
 0.1460362911    62   0.1156613683    63   0.2650100271    64   0.1592697337    65
 0.0920215396    66   0.1403723237    67   0.0801289455    68   0.0462892649    69
 0.0107835415    70   0.0244067802    71   0.0140992591    72   0.0039118995    73
 0.0117295466    74  -0.0077996863    75
# ORBITAL         12  NAO =      20
 0.0172973458    31   0.2021529787    32   0.1246606235    33  -0.0000031809    34
 0.3042972540    35   0.1970108564    36   0.0000068028    37   0.1300804271    38
 0.0908986389    39  -0.0079455903    40   0.0000048018    41  -0.0000039238    42
 0.0117793218    43   0.0139996205    44  -0.0073463152    45   0.4270402124    76
 0.1295468232    77  -0.0000053093    78  -0.0294631198    79  -0.0195166579    80
# ORBITAL         13  NAO =      20
-0.0173282009    31  -0.2022108198    32  -0.1243909531    33  -0.0000096109    34
 0.3043243458    35  -0.1970216211    36  -0.0000042424    37   0.1300749867    38
-0.0909331248    39   0.0079484887    40  -0.0000056809    41   0.0000028882    42
-0.0117996319    43   0.0139959547    44   0.0073369181    45  -0.4270900640    81
-0.1296000887    82   0.0000006580    83  -0.0294618950    84   0.0195172636    85
# ORBITAL         14  NAO =      20
 0.0173002408    46   0.2021118790    47   0.1246240723    48   0.0000022713    49
 0.3227889720    50   0.1649529052    51  -0.0000148620    52   0.1438492365    53
 0.0672219489    54  -0.0079367406    55   0.0000175697    56  -0.0000089690    57
 0.0079591066    58   0.0165643938    59  -0.0034869406    60   0.4270093758    86
 0.1295884488    87   0.0000016180    88  -0.0316194875    89  -0.0157531870    90
# ORBITAL         15  NAO =      20
-0.0173086687    46  -0.2021939367    47  -0.1245611168    48   0.0000003610    49
-0.0183875471    50   0.3620460821    51   0.0000673331    52  -0.0136415635    53
 0.1580963305    54   0.0079527536    55  -0.0000113874    56   0.0000032002    57
 0.0130569871    58  -0.0025806853    59  -0.0175049037    60  -0.4270744827    91
-0.1295400125    92   0.0000001650    93   0.0021637053    94  -0.0352738044    95
# ORBITAL         16  NAO =      20
-0.0173183346    61  -0.2022026360    62  -0.1245109940    63   0.0000075545    64
 0.0183988865    65   0.3620424314    66  -0.0000395096    67   0.0136658395    68
 0.1581128420    69   0.0079480868    70  -0.0000049906    71  -0.0000080201    72
 0.0130454991    73   0.0025855278    74  -0.0175242163    75  -0.4270686231    96
-0.1295457954    97  -0.0000005864    98  -0.0021655869    99  -0.0352696895   100
# ORBITAL         17  NAO =      20
 0.0173197873    61   0.2021511454    62   0.1244587778    63  -0.0000011094    64
-0.3228115619    65   0.1649560698    66   0.0000052783    67  -0.1438497907    68
 0.0671949240    69  -0.0079405965    70   0.0000104455    71  -0.0000034930    72
 0.0079482684    73  -0.0165642389    74  -0.0034671716    75   0.4270459111   101
 0.1296314976   102  -0.0000009897   103   0.0316266447   104  -0.0157561697   105
# ORBITAL         18  NAO =      15
-0.0163776922     1  -0.0583204663     2   0.1324850019     3  -0.6739726665     4
-0.0000444708     5  -0.0000310706     6  -0.4551573242     7  -0.0000875557     8
-0.0000314392     9  -0.0756705415    10  -0.0000033820    11  -0.0000057832    12
 0.0323892303    13   0.0000190463    14   0.0323603700    15
# ORBITAL         19  NAO =      15
-0.0163754625    16  -0.0583193461    17   0.1324498525    18   0.6739423059    19
 0.0000015891    20  -0.0000003256    21   0.4551921058    22  -0.0000787438    23
-0.0000153122    24  -0.0756649095    25   0.0000030203    26  -0.0000219594    27
 0.0323852880    28  -0.0000064669    29   0.0323956416    30
$END

In this input file, the “WFNTYP=DET” keyword means the wave function will be expressed in the basis of determinants. In this case, the wave function consists only one determinant, so we specify “NSTR=1” keyword. This determinant should be provided in $STR section. The format of writing a determinant is different from a structure. To write a determinant, we first write all the occupied \(\alpha\) orbitals (“1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18” in this case), followed by all the occupied \(\beta\) orbitals (“1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 19” in this case).

Note

In this case, the wave funtion contains only one determinant, and therefore the BOVB and VBSCF wave functions are identical.

The energy of QC state is -192.49514835 hartree, compared with the energy of totally 3 structures (-192.68236940 hartree), the bonding energy of the C-C bridge bond is 117.5 kcal/mol. Therefore, one can find the resonance energy of the C-C bond is 54 % of the bonding energy, and thus conclude the C-C bridge bond in the propellane compound is a charge-shift bond.