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QuantumPackage/src/tc_bi_ortho/h_biortho.irp.f
2023-02-07 17:07:49 +01:00

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! --
subroutine hmat_bi_ortho(key_j, key_i, Nint, hmono, htwoe, htot)
BEGIN_DOC
!
! < key_j | H | key_i > where | key_j > is developed on the LEFT basis and | key_i > is developed on the RIGHT basis
!
END_DOC
use bitmasks
implicit none
integer, intent(in) :: Nint
integer(bit_kind), intent(in) :: key_i(Nint,2), key_j(Nint,2)
double precision, intent(out) :: hmono, htwoe, htot
integer :: degree
hmono = 0.d0
htwoe = 0.d0
htot = 0.d0
call get_excitation_degree(key_i, key_j, degree, Nint)
if(degree .gt. 2) return
if(degree == 0) then
call diag_hmat_bi_ortho(Nint, key_i, hmono, htwoe)
htot = htot + nuclear_repulsion
else if (degree == 1) then
call single_hmat_bi_ortho(Nint, key_j, key_i, hmono, htwoe)
else if(degree == 2) then
call double_hmat_bi_ortho(Nint, key_j, key_i, hmono, htwoe)
endif
htot += hmono + htwoe
return
end subroutine hmat_bi_ortho
! ---
subroutine diag_hmat_bi_ortho(Nint, key_i, hmono, htwoe)
use bitmasks
implicit none
integer, intent(in) :: Nint
integer(bit_kind), intent(in) :: key_i(Nint,2)
double precision, intent(out) :: hmono, htwoe
integer :: occ(Nint*bit_kind_size,2)
integer :: Ne(2), i, j, ii, jj, ispin, jspin
hmono = 0.d0
htwoe = 0.d0
call bitstring_to_list_ab(key_i, occ, Ne, Nint)
do ispin = 1, 2
do i = 1, Ne(ispin)
ii = occ(i,ispin)
hmono += mo_bi_ortho_one_e(ii,ii)
enddo
enddo
! alpha/beta two-body
ispin = 1
jspin = 2
do i = 1, Ne(ispin) ! electron 1
ii = occ(i,ispin)
do j = 1, Ne(jspin) ! electron 2
jj = occ(j,jspin)
htwoe += mo_bi_ortho_coul_e(jj,ii,jj,ii)
enddo
enddo
! alpha/alpha two-body
do i = 1, Ne(ispin)
ii = occ(i,ispin)
do j = i+1, Ne(ispin)
jj = occ(j,ispin)
htwoe += mo_bi_ortho_coul_e(ii,jj,ii,jj) - mo_bi_ortho_coul_e(ii,jj,jj,ii)
enddo
enddo
! beta/beta two-body
do i = 1, Ne(jspin)
ii = occ(i,jspin)
do j = i+1, Ne(jspin)
jj = occ(j,jspin)
htwoe += mo_bi_ortho_coul_e(ii,jj,ii,jj) - mo_bi_ortho_coul_e(ii,jj,jj,ii)
enddo
enddo
return
end subroutine diag_hmat_bi_ortho
! ---
subroutine single_hmat_bi_ortho(Nint, key_j, key_i, hmono, htwoe)
BEGIN_DOC
!
! < key_j | H | key_i > for single excitation
!
END_DOC
use bitmasks
implicit none
integer, intent(in) :: Nint
integer(bit_kind), intent(in) :: key_j(Nint,2), key_i(Nint,2)
double precision, intent(out) :: hmono, htwoe
integer :: occ(Nint*bit_kind_size,2)
integer :: Ne(2), i, j, ii, ispin, jspin
integer :: degree,exc(0:2,2,2)
integer :: h1, p1, h2, p2, s1, s2
integer :: other_spin(2)
double precision :: phase
other_spin(1) = 2
other_spin(2) = 1
hmono = 0.d0
htwoe = 0.d0
call get_excitation_degree(key_i, key_j, degree, Nint)
if(degree .ne. 1) then
return
endif
call bitstring_to_list_ab(key_i, occ, Ne, Nint)
call get_single_excitation(key_i, key_j, exc, phase, Nint)
call decode_exc(exc, 1, h1, p1, h2, p2, s1, s2)
hmono = mo_bi_ortho_one_e(p1,h1) * phase
! alpha/beta two-body
ispin = other_spin(s1)
if(s1 == 1) then
! single alpha
do i = 1, Ne(ispin) ! electron 2
ii = occ(i,ispin)
htwoe += mo_bi_ortho_coul_e(ii,p1,ii,h1)
enddo
else
! single beta
do i = 1, Ne(ispin) ! electron 1
ii = occ(i,ispin)
htwoe += mo_bi_ortho_coul_e(p1,ii,h1,ii)
enddo
endif
! same spin two-body
do i = 1, Ne(s1)
ii = occ(i,s1)
! ( h1 p1 |ii ii ) - ( h1 ii | p1 ii )
htwoe += mo_bi_ortho_coul_e(ii,p1,ii,h1) - mo_bi_ortho_coul_e(p1,ii,ii,h1)
enddo
htwoe *= phase
end subroutine single_hmat_bi_ortho
! ---
subroutine double_hmat_bi_ortho(Nint, key_j, key_i, hmono, htwoe)
BEGIN_DOC
!
! < key_j | H | key_i> for double excitation
!
END_DOC
use bitmasks
implicit none
integer, intent(in) :: Nint
integer(bit_kind), intent(in) :: key_j(Nint,2), key_i(Nint,2)
double precision, intent(out) :: hmono, htwoe
integer :: occ(Nint*bit_kind_size,2)
integer :: Ne(2), i, j, ii, ispin, jspin
integer :: degree,exc(0:2,2,2)
integer :: h1, p1, h2, p2, s1, s2
integer :: other_spin(2)
double precision :: phase
other_spin(1) = 2
other_spin(2) = 1
call get_excitation_degree(key_i, key_j, degree, Nint)
hmono = 0.d0
htwoe = 0.d0
if(degree .ne. 2) then
return
endif
call bitstring_to_list_ab(key_i, occ, Ne, Nint)
call get_double_excitation(key_i, key_j, exc, phase, Nint)
call decode_exc(exc, 2, h1, p1, h2, p2, s1, s2)
if(s1 .ne. s2) then
htwoe = mo_bi_ortho_coul_e(p2,p1,h2,h1)
else
! same spin two-body
! direct terms exchange terms
htwoe = mo_bi_ortho_coul_e(p2,p1,h2,h1) - mo_bi_ortho_coul_e(p1,p2,h2,h1)
endif
htwoe *= phase
end subroutine double_hmat_bi_ortho
! ---