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| .. | ||
| 30.cisd.bats | ||
| cisd_routine.irp.f | ||
| cisd.irp.f | ||
| EZFIO.cfg | ||
| h_apply.irp.f | ||
| kpts_cisd.irp.f | ||
| NEED | ||
| README.rst | ||
==== cisd ==== This module contains a CI of single and double excitations. The user point of view ---------------------- The :command:`cisd` program performs the CI of the ROHF-like + all single and double 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 :c:func:`scf` program gave the lowest SCF solution. In combination with :c:func:`save_natorb` it can produce new |MOs| in order to reperform an :c:func:`scf` optimization. * **Excited states calculations**: generate guess for all the :option:`determinants n_states` wave functions, that will be used by the :c:func:`fci` program. The main keywords/options to be used are: * :option:`determinants n_states` : number of states to consider for the |cisd| calculation * :option:`determinants s2_eig` : force all states to have the desired value of :math:`S^2` * :option:`determinants expected_s2` : desired value of :math:`S^2` The programmer point of view ---------------------------- This module have been built by setting the following rules: * The only generator determinant is the Hartree-Fock (single-reference method) * All generated determinants are included in the wave function (no perturbative selection) These rules are set in the ``H_apply.irp.f`` file.