mirror of
https://github.com/QuantumPackage/qp2.git
synced 2024-11-07 22:53:52 +01:00
85 lines
2.4 KiB
Fortran
85 lines
2.4 KiB
Fortran
program cis
|
|
implicit none
|
|
BEGIN_DOC
|
|
!
|
|
! Configuration Interaction with Single excitations.
|
|
!
|
|
! This program takes a reference Slater determinant of ROHF-like
|
|
! occupancy, and performs all single excitations on top of it.
|
|
! Disregarding spatial symmetry, it computes the `n_states` lowest
|
|
! eigenstates of that CI matrix. (see :option:`determinants n_states`)
|
|
!
|
|
! This program can be useful in many cases:
|
|
!
|
|
!
|
|
! 1. Ground state calculation
|
|
!
|
|
! To be sure to have the lowest |SCF| solution, perform an :ref:`scf`
|
|
! (see the :ref:`module_hartree_fock` module), then a :ref:`cis`, save the
|
|
! natural orbitals (see :ref:`save_natorb`) and re-run an :ref:`scf`
|
|
! optimization from this |MO| guess.
|
|
!
|
|
!
|
|
! 2. Excited states calculations
|
|
!
|
|
! The lowest excited states are much likely to be dominated by
|
|
! single-excitations. Therefore, running a :ref:`cis` will save the
|
|
! `n_states` lowest states within the |CIS| space in the |EZFIO|
|
|
! directory, which can afterwards be used as guess wave functions for
|
|
! a further multi-state |FCI| calculation if :option:`determinants
|
|
! read_wf` is set to |true| before running the :ref:`fci` executable.
|
|
!
|
|
!
|
|
! If :option:`determinants s2_eig` is set to |true|, the |CIS|
|
|
! will only retain states having the expected |S^2| value (see
|
|
! :option:`determinants expected_s2`). Otherwise, the |CIS| will take
|
|
! the lowest :option:`determinants n_states`, whatever multiplicity
|
|
! they are.
|
|
!
|
|
! .. note::
|
|
!
|
|
! To discard some orbitals, use the :ref:`qp_set_mo_class`
|
|
! command to specify:
|
|
!
|
|
! * *core* orbitals which will be always doubly occupied
|
|
!
|
|
! * *act* orbitals where an electron can be either excited from or to
|
|
!
|
|
! * *del* orbitals which will be never occupied
|
|
!
|
|
END_DOC
|
|
read_wf = .False.
|
|
SOFT_TOUCH read_wf
|
|
call run
|
|
end
|
|
|
|
subroutine run
|
|
implicit none
|
|
integer :: i
|
|
|
|
if(pseudo_sym)then
|
|
call H_apply_cis_sym
|
|
else
|
|
call H_apply_cis
|
|
endif
|
|
print *, 'N_det = ', N_det
|
|
print*,'******************************'
|
|
print *, 'Energies of the states:'
|
|
do i = 1,N_states
|
|
print *, i, CI_energy(i)
|
|
enddo
|
|
if (N_states > 1) then
|
|
print*,'******************************'
|
|
print*,'Excitation energies '
|
|
do i = 2, N_states
|
|
print*, i ,CI_energy(i) - CI_energy(1)
|
|
enddo
|
|
endif
|
|
|
|
call ezfio_set_cis_energy(CI_energy)
|
|
psi_coef = ci_eigenvectors
|
|
SOFT_TOUCH psi_coef
|
|
call save_wavefunction
|
|
|
|
end
|