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https://github.com/QuantumPackage/qp2.git
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172 lines
5.1 KiB
Fortran
172 lines
5.1 KiB
Fortran
use bitmasks
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BEGIN_PROVIDER [ integer(bit_kind), psi_cas, (N_int,2,psi_det_size) ]
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&BEGIN_PROVIDER [ double precision, psi_cas_coef, (psi_det_size,n_states) ]
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&BEGIN_PROVIDER [ integer, idx_cas, (psi_det_size) ]
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&BEGIN_PROVIDER [ integer, N_det_cas ]
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implicit none
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BEGIN_DOC
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! |CAS| wave function, defined from the application of the |CAS| bitmask on the
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! determinants. idx_cas gives the indice of the |CAS| determinant in psi_det.
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END_DOC
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integer :: i, k, l
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logical :: good
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N_det_cas = 0
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do i=1,N_det
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do l = 1, N_states
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psi_cas_coef(i,l) = 0.d0
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enddo
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do l=1,n_cas_bitmask
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good = .True.
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do k=1,N_int
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good = good .and. ( &
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iand(not(cas_bitmask(k,1,l)), psi_det(k,1,i)) == &
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iand(not(cas_bitmask(k,1,l)), hf_bitmask(k,1)) ) .and. ( &
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iand(not(cas_bitmask(k,2,l)), psi_det(k,2,i)) == &
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iand(not(cas_bitmask(k,2,l)), hf_bitmask(k,2)) )
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enddo
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if (good) then
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exit
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endif
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enddo
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if (good) then
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N_det_cas = N_det_cas+1
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do k=1,N_int
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psi_cas(k,1,N_det_cas) = psi_det(k,1,i)
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psi_cas(k,2,N_det_cas) = psi_det(k,2,i)
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enddo
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idx_cas(N_det_cas) = i
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do k=1,N_states
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psi_cas_coef(N_det_cas,k) = psi_coef(i,k)
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enddo
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endif
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enddo
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call write_int(6,N_det_cas, 'Number of determinants in the CAS')
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END_PROVIDER
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BEGIN_PROVIDER [ integer(bit_kind), psi_cas_sorted_bit, (N_int,2,psi_det_size) ]
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&BEGIN_PROVIDER [ double precision, psi_cas_coef_sorted_bit, (psi_det_size,N_states) ]
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implicit none
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BEGIN_DOC
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! |CAS| determinants sorted to accelerate the search of a random determinant in the wave
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! function.
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END_DOC
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call sort_dets_by_det_search_key(N_det_cas, psi_cas, psi_cas_coef, size(psi_cas_coef,1), &
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psi_cas_sorted_bit, psi_cas_coef_sorted_bit, N_states)
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END_PROVIDER
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BEGIN_PROVIDER [ integer(bit_kind), psi_non_cas, (N_int,2,psi_det_size) ]
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&BEGIN_PROVIDER [ double precision, psi_non_cas_coef, (psi_det_size,n_states) ]
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&BEGIN_PROVIDER [ integer, idx_non_cas, (psi_det_size) ]
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&BEGIN_PROVIDER [ integer, N_det_non_cas ]
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implicit none
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BEGIN_DOC
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! Set of determinants which are not part of the |CAS|, defined from the application
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! of the |CAS| bitmask on the determinants.
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! idx_non_cas gives the indice of the determinant in psi_det.
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END_DOC
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integer :: i_non_cas,j,k
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integer :: degree
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logical :: in_cas
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i_non_cas =0
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do k=1,N_det
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in_cas = .False.
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do j=1,N_det_cas
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call get_excitation_degree(psi_cas(1,1,j), psi_det(1,1,k), degree, N_int)
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if (degree == 0) then
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in_cas = .True.
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exit
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endif
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enddo
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if (.not.in_cas) then
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double precision :: hij
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i_non_cas += 1
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do j=1,N_int
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psi_non_cas(j,1,i_non_cas) = psi_det(j,1,k)
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psi_non_cas(j,2,i_non_cas) = psi_det(j,2,k)
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enddo
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do j=1,N_states
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psi_non_cas_coef(i_non_cas,j) = psi_coef(k,j)
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enddo
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idx_non_cas(i_non_cas) = k
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endif
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enddo
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N_det_non_cas = i_non_cas
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END_PROVIDER
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BEGIN_PROVIDER [ integer(bit_kind), psi_non_cas_sorted_bit, (N_int,2,psi_det_size) ]
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&BEGIN_PROVIDER [ double precision, psi_non_cas_coef_sorted_bit, (psi_det_size,N_states) ]
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implicit none
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BEGIN_DOC
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! |CAS| determinants sorted to accelerate the search of a random determinant in the wave
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! function.
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END_DOC
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call sort_dets_by_det_search_key(N_det_cas, psi_non_cas, psi_non_cas_coef, size(psi_non_cas_coef,1), &
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psi_non_cas_sorted_bit, psi_non_cas_coef_sorted_bit, N_states)
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END_PROVIDER
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BEGIN_PROVIDER [double precision, H_matrix_cas, (N_det_cas,N_det_cas)]
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implicit none
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integer :: i,j
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double precision :: hij
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do i = 1, N_det_cas
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do j = 1, N_det_cas
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call i_H_j(psi_cas(1,1,i),psi_cas(1,1,j),N_int,hij)
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H_matrix_cas(i,j) = hij
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enddo
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enddo
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END_PROVIDER
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BEGIN_PROVIDER [double precision, psi_coef_cas_diagonalized, (N_det_cas,N_states)]
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&BEGIN_PROVIDER [double precision, psi_cas_energy_diagonalized, (N_states)]
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implicit none
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integer :: i,j
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double precision, allocatable :: eigenvectors(:,:), eigenvalues(:)
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allocate (eigenvectors(size(H_matrix_cas,1),N_det_cas))
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allocate (eigenvalues(N_det_cas))
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call lapack_diag(eigenvalues,eigenvectors, &
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H_matrix_cas,size(H_matrix_cas,1),N_det_cas)
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do i = 1, N_states
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psi_cas_energy_diagonalized(i) = eigenvalues(i)
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do j = 1, N_det_cas
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psi_coef_cas_diagonalized(j,i) = eigenvectors(j,i)
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enddo
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enddo
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END_PROVIDER
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BEGIN_PROVIDER [double precision, psi_cas_energy, (N_states)]
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implicit none
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BEGIN_DOC
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! Variational energy of $\Psi_{CAS}$, where $\Psi_{CAS} = \sum_{I \in CAS} \I \rangle \langle I | \Psi \rangle$.
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END_DOC
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integer :: i,j,k
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double precision :: hij,norm,u_dot_v
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psi_cas_energy = 0.d0
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do k = 1, N_states
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norm = 0.d0
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do i = 1, N_det_cas
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norm += psi_cas_coef(i,k) * psi_cas_coef(i,k)
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do j = 1, N_det_cas
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psi_cas_energy(k) += psi_cas_coef(i,k) * psi_cas_coef(j,k) * H_matrix_cas(i,j)
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enddo
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enddo
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psi_cas_energy(k) = psi_cas_energy(k) /norm
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enddo
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END_PROVIDER
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