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20.cis.bats | ||
cis.irp.f | ||
EZFIO.cfg | ||
h_apply.irp.f | ||
NEED | ||
README.rst |
=== cis === This module contains a |CIS| program. The user point of view ---------------------- The :ref:`cis` program performs the CI to obtain the ROHF reference + all single excitations on top of it. This program can be very useful to: * **Ground state calculations**: generate a guess for the ground state wave function if one is not sure that the :ref:`scf` program gave the lowest |SCF| solution. In combination with :ref:`save_natorb` it can produce new |MOs| in order to reperform an :ref:`scf` optimization. * **Excited states calculations**: generate guesses for all the :option:`determinants n_states` wave functions, that will be used by the :ref:`fci` program. The main keywords/options to be used are: * :option:`determinants n_states`: number of states to consider for the |CIS| calculation * :option:`determinants s2_eig`: force all states to have the desired value of |S^2| * :option:`determinants expected_s2`: desired value of |S^2| The programmer's point of view ------------------------------ This module was built by setting the following rules: * The only generator determinant is the Hartree-Fock (single-reference method) * All generated singly excited determinants are included in the wave function (no perturbative selection) These rules are set in the ``H_apply.irp.f`` file.