.. _cis:

.. program:: cis

.. default-role:: option

===
CIS
===

This module contains a CIS program, 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.





EZFIO parameters
----------------

.. option:: energy

    Variational |CIS| energy



Subroutines / functions
-----------------------



.. c:function:: cis

    .. code:: text

        subroutine cis

    File: :file:`cis.irp.f`

    Configuration Interaction with Single excitations.





.. c:function:: h_apply_cis

    .. code:: text

        subroutine H_apply_cis()

    File: :file:`h_apply.irp.f_shell_8`

    Calls H_apply on the HF determinant and selects all connected single and double excitations (of the same symmetry). Auto-generated by the ``generate_h_apply`` script.





.. c:function:: h_apply_cis_diexc

    .. code:: text

        subroutine H_apply_cis_diexc(key_in, key_prev, hole_1,particl_1, hole_2, particl_2, fock_diag_tmp, i_generator, iproc_in  )

    File: :file:`h_apply.irp.f_shell_8`

    





.. c:function:: h_apply_cis_diexcorg

    .. code:: text

        subroutine H_apply_cis_diexcOrg(key_in,key_mask,hole_1,particl_1,hole_2, particl_2, fock_diag_tmp, i_generator, iproc_in  )

    File: :file:`h_apply.irp.f_shell_8`

    Generate all double excitations of key_in using the bit masks of holes and particles. Assume N_int is already provided.





.. c:function:: h_apply_cis_diexcp

    .. code:: text

        subroutine H_apply_cis_diexcP(key_in, fs1, fh1, particl_1, fs2, fh2, particl_2, fock_diag_tmp, i_generator, iproc_in  )

    File: :file:`h_apply.irp.f_shell_8`

    





.. c:function:: h_apply_cis_monoexc

    .. code:: text

        subroutine H_apply_cis_monoexc(key_in, hole_1,particl_1,fock_diag_tmp,i_generator,iproc_in  )

    File: :file:`h_apply.irp.f_shell_8`

    Generate all single excitations of key_in using the bit masks of holes and particles. Assume N_int is already provided.