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quantum_package/docs/source/modules/kohn_sham.rst
2018-12-28 19:50:28 +01:00

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.. _kohn_sham:
.. program:: kohn_sham
.. default-role:: option
=========
kohn_sham
=========
The Kohn-Sham module performs *Restricted* Kohn-Sham calculations (the
spatial part of the |MOs| is common for alpha and beta spinorbitals).
The Kohn-Sham in an SCF and therefore is based on the ``scf_utils`` structure.
It performs the following actions:
#. Compute/Read all the one- and two-electron integrals, and store them in memory
#. Check in the |EZFIO| database if there is a set of |MOs|. If there is, it
will read them as initial guess. Otherwise, it will create a guess.
#. Perform the |SCF| iterations
The definition of the Fock matrix is in :file:`kohn_sham fock_matrix_ks.irp.f`
For the keywords related to the |SCF| procedure, see the ``scf_utils`` directory where you will find all options.
The main are:
# :option:`scf_utils thresh_scf`
# :option:`scf_utils level_shift`
At each iteration, the |MOs| are saved in the |EZFIO| database. Hence, if the calculation
crashes for any unexpected reason, the calculation can be restarted by running again
the |SCF| with the same |EZFIO| database.
The `DIIS`_ algorithm is implemented, as well as the `level-shifting`_ method.
If the |SCF| does not converge, try again with a higher value of :option:`level_shift`.
To start a calculation from scratch, the simplest way is to remove the
``mo_basis`` directory from the |EZFIO| database, and run the |SCF| again.
.. _DIIS: https://en.wikipedia.org/w/index.php?title=DIIS
.. _level-shifting: https://doi.org/10.1002/qua.560070407
Providers
---------
.. c:var:: ao_bi_elec_integral_alpha
.. code:: text
double precision, allocatable :: ao_bi_elec_integral_alpha (ao_num,ao_num)
double precision, allocatable :: ao_bi_elec_integral_beta (ao_num,ao_num)
File: :file:`fock_matrix_ks.irp.f`
Alpha Fock matrix in ao basis set
.. c:var:: ao_bi_elec_integral_beta
.. code:: text
double precision, allocatable :: ao_bi_elec_integral_alpha (ao_num,ao_num)
double precision, allocatable :: ao_bi_elec_integral_beta (ao_num,ao_num)
File: :file:`fock_matrix_ks.irp.f`
Alpha Fock matrix in ao basis set
.. c:var:: ao_potential_alpha_xc
.. code:: text
double precision, allocatable :: ao_potential_alpha_xc (ao_num,ao_num)
double precision, allocatable :: ao_potential_beta_xc (ao_num,ao_num)
File: :file:`pot_functionals.irp.f`
.. c:var:: ao_potential_beta_xc
.. code:: text
double precision, allocatable :: ao_potential_alpha_xc (ao_num,ao_num)
double precision, allocatable :: ao_potential_beta_xc (ao_num,ao_num)
File: :file:`pot_functionals.irp.f`
.. c:var:: e_correlation_dft
.. code:: text
double precision :: e_correlation_dft
File: :file:`pot_functionals.irp.f`
.. c:var:: e_exchange_dft
.. code:: text
double precision :: e_exchange_dft
File: :file:`pot_functionals.irp.f`
.. c:var:: extra_e_contrib_density
.. code:: text
double precision :: extra_e_contrib_density
File: :file:`ks_enery.irp.f`
Extra contribution to the SCF energy coming from the density.
For a Hartree-Fock calculation: extra_e_contrib_density = 0
For a Kohn-Sham or Range-separated Kohn-Sham: the exchange/correlation - 1/2 trace of the V_xc potential
.. c:var:: fock_matrix_alpha_no_xc_ao
.. code:: text
double precision, allocatable :: fock_matrix_alpha_no_xc_ao (ao_num,ao_num)
double precision, allocatable :: fock_matrix_beta_no_xc_ao (ao_num,ao_num)
File: :file:`fock_matrix_ks.irp.f`
Mono electronic an Coulomb matrix in ao basis set
.. c:var:: fock_matrix_ao_alpha
.. code:: text
double precision, allocatable :: fock_matrix_ao_alpha (ao_num,ao_num)
double precision, allocatable :: fock_matrix_ao_beta (ao_num,ao_num)
File: :file:`fock_matrix_ks.irp.f`
Alpha Fock matrix in ao basis set
.. c:var:: fock_matrix_ao_beta
.. code:: text
double precision, allocatable :: fock_matrix_ao_alpha (ao_num,ao_num)
double precision, allocatable :: fock_matrix_ao_beta (ao_num,ao_num)
File: :file:`fock_matrix_ks.irp.f`
Alpha Fock matrix in ao basis set
.. c:var:: fock_matrix_beta_no_xc_ao
.. code:: text
double precision, allocatable :: fock_matrix_alpha_no_xc_ao (ao_num,ao_num)
double precision, allocatable :: fock_matrix_beta_no_xc_ao (ao_num,ao_num)
File: :file:`fock_matrix_ks.irp.f`
Mono electronic an Coulomb matrix in ao basis set
.. c:var:: fock_matrix_energy
.. code:: text
double precision :: ks_energy
double precision :: two_electron_energy
double precision :: one_electron_energy
double precision :: fock_matrix_energy
double precision :: trace_potential_xc
File: :file:`ks_enery.irp.f`
Kohn-Sham energy containing the nuclear repulsion energy, and the various components of this quantity.
.. c:var:: ks_energy
.. code:: text
double precision :: ks_energy
double precision :: two_electron_energy
double precision :: one_electron_energy
double precision :: fock_matrix_energy
double precision :: trace_potential_xc
File: :file:`ks_enery.irp.f`
Kohn-Sham energy containing the nuclear repulsion energy, and the various components of this quantity.
.. c:var:: one_electron_energy
.. code:: text
double precision :: ks_energy
double precision :: two_electron_energy
double precision :: one_electron_energy
double precision :: fock_matrix_energy
double precision :: trace_potential_xc
File: :file:`ks_enery.irp.f`
Kohn-Sham energy containing the nuclear repulsion energy, and the various components of this quantity.
.. c:var:: trace_potential_xc
.. code:: text
double precision :: ks_energy
double precision :: two_electron_energy
double precision :: one_electron_energy
double precision :: fock_matrix_energy
double precision :: trace_potential_xc
File: :file:`ks_enery.irp.f`
Kohn-Sham energy containing the nuclear repulsion energy, and the various components of this quantity.
.. c:var:: two_electron_energy
.. code:: text
double precision :: ks_energy
double precision :: two_electron_energy
double precision :: one_electron_energy
double precision :: fock_matrix_energy
double precision :: trace_potential_xc
File: :file:`ks_enery.irp.f`
Kohn-Sham energy containing the nuclear repulsion energy, and the various components of this quantity.
Subroutines / functions
-----------------------
.. c:function:: check_coherence_functional
.. code:: text
subroutine check_coherence_functional
File: :file:`ks_scf.irp.f`
.. c:function:: create_guess
.. code:: text
subroutine create_guess
File: :file:`ks_scf.irp.f`
Create a MO guess if no MOs are present in the EZFIO directory
.. c:function:: run
.. code:: text
subroutine run
File: :file:`ks_scf.irp.f`
Run SCF calculation
.. c:function:: srs_ks_cf
.. code:: text
subroutine srs_ks_cf
File: :file:`ks_scf.irp.f`
Produce `Kohn_Sham` MO orbital output: mo_basis.mo_tot_num mo_basis.mo_label mo_basis.ao_md5 mo_basis.mo_coef mo_basis.mo_occ output: kohn_sham.energy optional: mo_basis.mo_coef