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mirror of https://github.com/QuantumPackage/qp2.git synced 2024-07-23 02:57:24 +02:00
qp2/src/determinants/psi_cas.irp.f

170 lines
5.1 KiB
Fortran

use bitmasks
BEGIN_PROVIDER [ integer(bit_kind), psi_cas, (N_int,2,psi_det_size) ]
&BEGIN_PROVIDER [ double precision, psi_cas_coef, (psi_det_size,n_states) ]
&BEGIN_PROVIDER [ integer, idx_cas, (psi_det_size) ]
&BEGIN_PROVIDER [ integer, N_det_cas ]
implicit none
BEGIN_DOC
! |CAS| wave function, defined from the application of the |CAS| bitmask on the
! determinants. idx_cas gives the indice of the |CAS| determinant in psi_det.
END_DOC
integer :: i, k, l
logical :: good
N_det_cas = 0
do i=1,N_det
do l = 1, N_states
psi_cas_coef(i,l) = 0.d0
enddo
good = .True.
do k=1,N_int
good = good .and. ( &
iand(not(act_bitmask(k,1)), psi_det(k,1,i)) == &
iand(not(act_bitmask(k,1)), hf_bitmask(k,1)) ) .and. ( &
iand(not(act_bitmask(k,2)), psi_det(k,2,i)) == &
iand(not(act_bitmask(k,2)), hf_bitmask(k,2)) )
enddo
if (good) then
exit
endif
if (good) then
N_det_cas = N_det_cas+1
do k=1,N_int
psi_cas(k,1,N_det_cas) = psi_det(k,1,i)
psi_cas(k,2,N_det_cas) = psi_det(k,2,i)
enddo
idx_cas(N_det_cas) = i
do k=1,N_states
psi_cas_coef(N_det_cas,k) = psi_coef(i,k)
enddo
endif
enddo
call write_int(6,N_det_cas, 'Number of determinants in the CAS')
END_PROVIDER
BEGIN_PROVIDER [ integer(bit_kind), psi_cas_sorted_bit, (N_int,2,psi_det_size) ]
&BEGIN_PROVIDER [ double precision, psi_cas_coef_sorted_bit, (psi_det_size,N_states) ]
implicit none
BEGIN_DOC
! |CAS| determinants sorted to accelerate the search of a random determinant in the wave
! function.
END_DOC
call sort_dets_by_det_search_key(N_det_cas, psi_cas, psi_cas_coef, size(psi_cas_coef,1), &
psi_cas_sorted_bit, psi_cas_coef_sorted_bit, N_states)
END_PROVIDER
BEGIN_PROVIDER [ integer(bit_kind), psi_non_cas, (N_int,2,psi_det_size) ]
&BEGIN_PROVIDER [ double precision, psi_non_cas_coef, (psi_det_size,n_states) ]
&BEGIN_PROVIDER [ integer, idx_non_cas, (psi_det_size) ]
&BEGIN_PROVIDER [ integer, N_det_non_cas ]
implicit none
BEGIN_DOC
! Set of determinants which are not part of the |CAS|, defined from the application
! of the |CAS| bitmask on the determinants.
! idx_non_cas gives the indice of the determinant in psi_det.
END_DOC
integer :: i_non_cas,j,k
integer :: degree
logical :: in_cas
i_non_cas =0
do k=1,N_det
in_cas = .False.
do j=1,N_det_cas
call get_excitation_degree(psi_cas(1,1,j), psi_det(1,1,k), degree, N_int)
if (degree == 0) then
in_cas = .True.
exit
endif
enddo
if (.not.in_cas) then
double precision :: hij
i_non_cas += 1
do j=1,N_int
psi_non_cas(j,1,i_non_cas) = psi_det(j,1,k)
psi_non_cas(j,2,i_non_cas) = psi_det(j,2,k)
enddo
do j=1,N_states
psi_non_cas_coef(i_non_cas,j) = psi_coef(k,j)
enddo
idx_non_cas(i_non_cas) = k
endif
enddo
N_det_non_cas = i_non_cas
END_PROVIDER
BEGIN_PROVIDER [ integer(bit_kind), psi_non_cas_sorted_bit, (N_int,2,psi_det_size) ]
&BEGIN_PROVIDER [ double precision, psi_non_cas_coef_sorted_bit, (psi_det_size,N_states) ]
implicit none
BEGIN_DOC
! |CAS| determinants sorted to accelerate the search of a random determinant in the wave
! function.
END_DOC
call sort_dets_by_det_search_key(N_det_cas, psi_non_cas, psi_non_cas_coef, size(psi_non_cas_coef,1), &
psi_non_cas_sorted_bit, psi_non_cas_coef_sorted_bit, N_states)
END_PROVIDER
BEGIN_PROVIDER [double precision, H_matrix_cas, (N_det_cas,N_det_cas)]
implicit none
integer :: i,j
double precision :: hij
do i = 1, N_det_cas
do j = 1, N_det_cas
call i_H_j(psi_cas(1,1,i),psi_cas(1,1,j),N_int,hij)
H_matrix_cas(i,j) = hij
enddo
enddo
END_PROVIDER
BEGIN_PROVIDER [double precision, psi_coef_cas_diagonalized, (N_det_cas,N_states)]
&BEGIN_PROVIDER [double precision, psi_cas_energy_diagonalized, (N_states)]
implicit none
integer :: i,j
double precision, allocatable :: eigenvectors(:,:), eigenvalues(:)
allocate (eigenvectors(size(H_matrix_cas,1),N_det_cas))
allocate (eigenvalues(N_det_cas))
call lapack_diag(eigenvalues,eigenvectors, &
H_matrix_cas,size(H_matrix_cas,1),N_det_cas)
do i = 1, N_states
psi_cas_energy_diagonalized(i) = eigenvalues(i)
do j = 1, N_det_cas
psi_coef_cas_diagonalized(j,i) = eigenvectors(j,i)
enddo
enddo
END_PROVIDER
BEGIN_PROVIDER [double precision, psi_cas_energy, (N_states)]
implicit none
BEGIN_DOC
! Variational energy of $\Psi_{CAS}$, where $\Psi_{CAS} = \sum_{I \in CAS} \I \rangle \langle I | \Psi \rangle$.
END_DOC
integer :: i,j,k
double precision :: hij,norm,u_dot_v
psi_cas_energy = 0.d0
do k = 1, N_states
norm = 0.d0
do i = 1, N_det_cas
norm += psi_cas_coef(i,k) * psi_cas_coef(i,k)
do j = 1, N_det_cas
psi_cas_energy(k) += psi_cas_coef(i,k) * psi_cas_coef(j,k) * H_matrix_cas(i,j)
enddo
enddo
psi_cas_energy(k) = psi_cas_energy(k) /norm
enddo
END_PROVIDER