.. _tutorial_es_methods:

Methods for excited states
==========================================

Here we briefly overview the electronic structure methods supported by MLatom via interfaces:

- TDDFT and TDA via interface to PySCF.
- TDDFT via interface to Gaussian.
- :ref:`AIQM1 <tutorial_aiqm1>` and other semi-empirical QM methods implemented in the :ref:`MNDO <install_MNDO>` program. The excited-state properties can be calculated with fast CIS or slow MR-CI approaches with the above Hamiltonians. Note that AIQM1 also requires installation of :ref:`TorchANI <install_TorchANI>` and :ref:`dftd4 <install_dftd4>` programs.
- CASSCF via the interface to :ref:`COLUMBUS <install_COLUMBUS>`.
- ADC(2) via interface to :ref:`Turbomole <install_Turbomole>`.

These methods support calculations of various excited-state properties such as energies, forces, oscillator strengths, and, often, nonadiabatic couplings.

See our paper for more details (please also cite it if you use the corresponding features):

- Lina Zhang, Sebastian Pios, Mikołaj Martyka, Fuchun Ge, Yi-Fan Hou, Yuxinxin Chen, Joanna Jankowska, Lipeng Chen, Mario Barbatti, `Pavlo O. Dral <http://dr-dral.com>`__. `MLatom software ecosystem for surface hopping dynamics in Python with quantum mechanical and machine learning methods <https://doi.org/10.1021/acs.jctc.4c00468>`__. *J. Chem. Theory Comput.* **2024**, *20*, 5043--5057. DOI: 10.1021/acs.jctc.4c00468. Preprint on *arXiv*: https://arxiv.org/abs/2404.06189.

.. note:

    Only TDDFT and TDA through interface to PySCF are provided on the XACS cloud platform due to the license restrictions of other programs.