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.. | ||
damping_scf.irp.f | ||
diagonalize_fock.irp.f | ||
diis.irp.f | ||
EZFIO.cfg | ||
fock_matrix.irp.f | ||
huckel.irp.f | ||
NEED | ||
README.rst | ||
roothaan_hall_scf.irp.f | ||
scf_density_matrix_ao.irp.f |
========= scf_utils ========= The scf_utils module is an abstract module which contains the basics to perform *Restricted* SCF calculations (the spatial part of the |MOs| is common for alpha and beta spinorbitals) based on a single-determinant wave function. This module does not produce any executable *and must not do*, but instead it contains everything one needs to perform an orbital optimization based on an Fock matrix. The ``scf_utils`` module is meant to be included in the :file:`NEED` of the various single determinant SCF procedures, such as ``hartree_fock`` or ``kohn_sham``, where a specific definition of the Fock matrix is given (see :file:`hartree_fock fock_matrix_hf.irp.f` for an example). All SCF programs perform 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 based on the definition of the Fock matrix The main keywords/options 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