2014-05-22 11:17:36 +02:00
|
|
|
subroutine pt2_moller_plesset(det_pert,c_pert,e_2_pert,H_pert_diag,Nint,ndet,n_st)
|
|
|
|
|
use bitmasks
|
|
|
|
|
implicit none
|
|
|
|
|
integer, intent(in) :: Nint,ndet,n_st
|
|
|
|
|
integer(bit_kind), intent(in) :: det_pert(Nint,2)
|
|
|
|
|
double precision , intent(out) :: c_pert(n_st),e_2_pert(n_st),H_pert_diag
|
|
|
|
|
double precision :: i_H_psi_array(N_st)
|
|
|
|
|
|
|
|
|
|
BEGIN_DOC
|
|
|
|
|
! compute the standard Moller-Plesset perturbative first order coefficient and second order energetic contribution
|
|
|
|
|
!
|
|
|
|
|
! for the various n_st states.
|
|
|
|
|
!
|
|
|
|
|
! c_pert(i) = <psi(i)|H|det_pert>/(difference of orbital energies)
|
|
|
|
|
!
|
|
|
|
|
! e_2_pert(i) = <psi(i)|H|det_pert>^2/(difference of orbital energies)
|
|
|
|
|
!
|
|
|
|
|
END_DOC
|
|
|
|
|
|
|
|
|
|
integer :: i,j
|
|
|
|
|
double precision :: diag_H_mat_elem
|
|
|
|
|
integer :: exc(0:2,2,2)
|
|
|
|
|
integer :: degree
|
|
|
|
|
double precision :: phase,delta_e
|
|
|
|
|
integer :: h1,h2,p1,p2,s1,s2
|
|
|
|
|
ASSERT (Nint == N_int)
|
|
|
|
|
ASSERT (Nint > 0)
|
2014-05-27 17:30:44 +02:00
|
|
|
call get_excitation(ref_bitmask,det_pert,exc,degree,phase,Nint)
|
2014-05-22 11:17:36 +02:00
|
|
|
call decode_exc(exc,degree,h1,p1,h2,p2,s1,s2)
|
|
|
|
|
delta_e = Fock_matrix_diag_mo(h1) + Fock_matrix_diag_mo(h2) - &
|
2014-05-27 17:30:44 +02:00
|
|
|
(Fock_matrix_diag_mo(p1) + Fock_matrix_diag_mo(p2))
|
2014-05-22 11:17:36 +02:00
|
|
|
delta_e = 1.d0/delta_e
|
|
|
|
|
|
2014-05-27 17:30:44 +02:00
|
|
|
call i_H_psi(det_pert,psi_selectors,psi_selectors_coef,Nint,N_det,psi_selectors_size,n_st,i_H_psi_array)
|
2014-05-22 11:17:36 +02:00
|
|
|
H_pert_diag = diag_H_mat_elem(det_pert,Nint)
|
|
|
|
|
do i =1,n_st
|
|
|
|
|
c_pert(i) = i_H_psi_array(i) *delta_e
|
|
|
|
|
e_2_pert(i) = c_pert(i) * i_H_psi_array(i)
|
|
|
|
|
enddo
|
|
|
|
|
|
|
|
|
|
end
|
