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133 lines
4.1 KiB
Fortran
133 lines
4.1 KiB
Fortran
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BEGIN_PROVIDER [ double precision, tc_two_rdm, (mo_num, mo_num, mo_num, mo_num)]
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implicit none
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BEGIN_DOC
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! tc_two_rdm(p,s,q,r) = <Phi| a^dager_p
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END_DOC
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integer :: i,j,istate,m,mm,nn
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integer :: exc(0:2,2,2)
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double precision :: phase
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double precision :: contrib
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integer :: h1,p1,s1,h2,p2,s2,degree
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integer, allocatable :: occ(:,:)
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integer :: n_occ_ab(2),other_spin(2)
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other_spin(1) = 2
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other_spin(2) = 1
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allocate(occ(N_int*bit_kind_size,2))
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tc_two_rdm = 0.d0
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do i = 1, N_det ! psi_left
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do j = 1, N_det ! psi_right
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call get_excitation_degree(psi_det(1,1,i),psi_det(1,1,j),degree,N_int)
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if(degree.gt.2)cycle
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if(degree.gt.0)then
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! get excitation operators: from psi_det(j) --> psi_det(i)
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call get_excitation(psi_det(1,1,j),psi_det(1,1,i),exc,degree,phase,N_int)
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call decode_exc(exc,degree,h1,p1,h2,p2,s1,s2)
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contrib = psi_l_coef_bi_ortho(i,1) * psi_r_coef_bi_ortho(j,1) * phase * state_average_weight(1)
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do istate = 2, N_states
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contrib += psi_l_coef_bi_ortho(i,istate) * psi_r_coef_bi_ortho(j,istate) * phase * state_average_weight(istate)
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enddo
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if(degree == 2)then
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call update_tc_rdm(h1,p1,h2,p2,s1,s2,tc_two_rdm,mo_num,contrib)
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else if(degree==1)then
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! cycle
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! occupation of the determinant psi_det(j)
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call bitstring_to_list_ab(psi_det(1,1,j), occ, n_occ_ab, N_int)
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! run over the electrons of opposite spin than the excitation
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s2 = other_spin(s1)
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do mm = 1, n_occ_ab(s2)
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m = occ(mm,s2)
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h2 = m
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p2 = m
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call update_tc_rdm(h1,p1,h2,p2,s1,s2,tc_two_rdm,mo_num,contrib)
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enddo
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! run over the electrons of same spin than the excitation
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s2 = s1
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do mm = 1, n_occ_ab(s2)
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m = occ(mm,s2)
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h2 = m
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p2 = m
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if(h2.le.h1)cycle
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call update_tc_rdm(h1,p1,h2,p2,s1,s2,tc_two_rdm,mo_num,contrib)
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enddo
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endif
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else if(degree == 0)then
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contrib = psi_l_coef_bi_ortho(i,1) * psi_r_coef_bi_ortho(j,1) * state_average_weight(1)
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! print*,'contrib',contrib
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do istate = 2, N_states
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contrib += psi_l_coef_bi_ortho(i,istate) * psi_r_coef_bi_ortho(j,istate) * state_average_weight(istate)
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enddo
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! occupation of the determinant psi_det(j)
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call bitstring_to_list_ab(psi_det(1,1,j), occ, n_occ_ab, N_int)
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s1 = 1 ! alpha electrons
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do nn = 1, n_occ_ab(s1)
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h1 = occ(nn,s1)
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p1 = occ(nn,s1)
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! run over the couple of alpha-beta electrons
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s2 = other_spin(s1)
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do mm = 1, n_occ_ab(s2)
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m = occ(mm,s2)
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h2 = m
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p2 = m
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call update_tc_rdm(h1,p1,h2,p2,s1,s2,tc_two_rdm,mo_num,contrib)
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enddo
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! run over the couple of alpha-alpha electrons
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s2 = s1
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do mm = 1, n_occ_ab(s2)
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m = occ(mm,s2)
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h2 = m
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p2 = m
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if(h2.le.h1)cycle
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call update_tc_rdm(h1,p1,h2,p2,s1,s2,tc_two_rdm,mo_num,contrib)
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enddo
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enddo
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s1 = 2
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do nn = 1, n_occ_ab(s1)
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h1 = occ(nn,s1)
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p1 = occ(nn,s1)
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! run over the couple of beta-beta electrons
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s2 = s1
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do mm = 1, n_occ_ab(s2)
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m = occ(mm,s2)
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h2 = m
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p2 = m
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if(h2.le.h1)cycle
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call update_tc_rdm(h1,p1,h2,p2,s1,s2,tc_two_rdm,mo_num,contrib)
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enddo
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enddo
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endif
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enddo
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enddo
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END_PROVIDER
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subroutine update_tc_rdm(h1,p1,h2,p2,s1,s2,array,sze,contrib)
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implicit none
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integer, intent(in) :: h1,p1,h2,p2,s1,s2,sze
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double precision, intent(in) :: contrib
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double precision, intent(inout) :: array(sze, sze, sze, sze)
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integer :: istate
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if(s1.ne.s2)then
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array(p1,h1,p2,h2) += contrib
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! permutation for particle symmetry
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array(p2,h2,p1,h1) += contrib
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else ! same spin double excitation
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array(p1,h1,p2,h2) += contrib
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! exchange
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! exchanging the holes
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array(p2,h1,p1,h2) -= contrib
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! exchanging the particles
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array(p1,h2,p2,h1) -= contrib
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! permutation for particle symmetry
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array(p2,h2,p1,h1) += contrib
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! exchange
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! exchanging the holes
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array(p1,h2,p2,h1) -= contrib
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! exchanging the particles
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array(p2,h1,p1,h2) -= contrib
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endif
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end
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