qp2/docs/source/modules/cis.rst

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.. _module_cis:
.. program:: cis
.. default-role:: option
===
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.
EZFIO parameters
----------------
.. option:: energy
Variational |CIS| energy
Programs
--------
* :ref:`cis`
Subroutines / functions
-----------------------
.. c:function:: h_apply_cis:
File : :file:`h_apply.irp.f_shell_8`
.. code:: fortran
subroutine H_apply_cis()
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.
Needs:
.. hlist::
:columns: 3
* :c:data:`psi_coef`
* :c:data:`n_states`
* :c:data:`generators_bitmask`
* :c:data:`mo_num`
* :c:data:`mo_two_e_integrals_in_map`
* :c:data:`h_apply_buffer_allocated`
* :c:data:`n_det`
* :c:data:`s2_eig`
* :c:data:`n_det_generators`
* :c:data:`i_bitmask_gen`
* :c:data:`n_int`
* :c:data:`psi_det`
* :c:data:`psi_det_generators`
* :c:data:`psi_det_generators`
Calls:
.. hlist::
:columns: 3
* :c:func:`build_fock_tmp`
* :c:func:`copy_h_apply_buffer_to_wf`
* :c:func:`dsort`
* :c:func:`h_apply_cis_diexc`
* :c:func:`h_apply_cis_monoexc`
* :c:func:`make_s2_eigenfunction`
* :c:func:`wall_time`
Touches:
.. hlist::
:columns: 3
* :c:data:`n_det`
* :c:data:`psi_occ_pattern`
* :c:data:`c0_weight`
* :c:data:`psi_coef`
* :c:data:`psi_det_sorted_bit`
* :c:data:`psi_det`
* :c:data:`psi_det_size`
* :c:data:`psi_det_sorted_bit`
* :c:data:`psi_occ_pattern`
.. c:function:: h_apply_cis_diexc:
File : :file:`h_apply.irp.f_shell_8`
.. code:: fortran
subroutine H_apply_cis_diexc(key_in, key_prev, hole_1,particl_1, hole_2, particl_2, fock_diag_tmp, i_generator, iproc_in )
Needs:
.. hlist::
:columns: 3
* :c:data:`n_int`
* :c:data:`n_det`
* :c:data:`mo_num`
Called by:
.. hlist::
:columns: 3
* :c:func:`h_apply_cis`
Calls:
.. hlist::
:columns: 3
* :c:func:`h_apply_cis_diexcp`
.. c:function:: h_apply_cis_diexcorg:
File : :file:`h_apply.irp.f_shell_8`
.. code:: fortran
subroutine H_apply_cis_diexcOrg(key_in,key_mask,hole_1,particl_1,hole_2, particl_2, fock_diag_tmp, i_generator, iproc_in )
Generate all double excitations of key_in using the bit masks of holes and
particles.
Assume N_int is already provided.
Needs:
.. hlist::
:columns: 3
* :c:data:`n_int`
* :c:data:`elec_alpha_num`
* :c:data:`mo_num`
Called by:
.. hlist::
:columns: 3
* :c:func:`h_apply_cis_diexcp`
Calls:
.. hlist::
:columns: 3
* :c:func:`bitstring_to_list_ab`
* :c:func:`fill_h_apply_buffer_no_selection`
.. c:function:: h_apply_cis_diexcp:
File : :file:`h_apply.irp.f_shell_8`
.. code:: fortran
subroutine H_apply_cis_diexcP(key_in, fs1, fh1, particl_1, fs2, fh2, particl_2, fock_diag_tmp, i_generator, iproc_in )
Needs:
.. hlist::
:columns: 3
* :c:data:`n_int`
* :c:data:`n_det`
* :c:data:`mo_num`
Called by:
.. hlist::
:columns: 3
* :c:func:`h_apply_cis_diexc`
Calls:
.. hlist::
:columns: 3
* :c:func:`h_apply_cis_diexcorg`
.. c:function:: h_apply_cis_monoexc:
File : :file:`h_apply.irp.f_shell_8`
.. code:: fortran
subroutine H_apply_cis_monoexc(key_in, hole_1,particl_1,fock_diag_tmp,i_generator,iproc_in )
Generate all single excitations of key_in using the bit masks of holes and
particles.
Assume N_int is already provided.
Needs:
.. hlist::
:columns: 3
* :c:data:`n_int`
* :c:data:`elec_alpha_num`
* :c:data:`mo_num`
Called by:
.. hlist::
:columns: 3
* :c:func:`h_apply_cis`
Calls:
.. hlist::
:columns: 3
* :c:func:`bitstring_to_list_ab`
* :c:func:`fill_h_apply_buffer_no_selection`