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https://github.com/pfloos/quack
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76 lines
1.6 KiB
Fortran
76 lines
1.6 KiB
Fortran
subroutine linear_response_D_pp(ispin,nBas,nC,nO,nV,nR,nOO,nVV,e,ERI,D_pp)
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! Compute the D matrix of the pp channel
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implicit none
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include 'parameters.h'
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! Input variables
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integer,intent(in) :: ispin
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integer,intent(in) :: nBas,nC,nO,nV,nR,nOO,nVV
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double precision,intent(in) :: e(nBas),ERI(nBas,nBas,nBas,nBas)
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! Local variables
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double precision :: eF
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double precision,external :: Kronecker_delta
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integer :: i,j,k,l,ij,kl
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! Output variables
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double precision,intent(out) :: D_pp(nOO,nOO)
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! Define the chemical potential
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eF = e(nO) + e(nO+1)
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! Build the D matrix for the singlet manifold
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if(ispin == 1) then
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ij = 0
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do i=nC+1,nO
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do j=nC+1,i
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ij = ij + 1
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kl = 0
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do k=nC+1,nO
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do l=nC+1,k
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kl = kl + 1
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D_pp(ij,kl) = - (e(i) + e(j) - eF)*Kronecker_delta(i,k)*Kronecker_delta(j,l) &
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+ ERI(k,l,i,j) - ERI(k,l,j,i)
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end do
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end do
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end do
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end do
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end if
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! Build the D matrix for the triplet manifold
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if(ispin == 2) then
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ij = 0
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do i=nC+1,nO
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do j=nC+1,i-1
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ij = ij + 1
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kl = 0
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do k=nC+1,nO
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do l=nC+1,k-1
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kl = kl + 1
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D_pp(ij,kl) = - (e(i) + e(j) - eF)*Kronecker_delta(i,k)*Kronecker_delta(j,l) &
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+ (ERI(k,l,i,j) + ERI(k,l,j,i))/sqrt((1d0 + Kronecker_delta(i,j))*(1d0 + Kronecker_delta(k,l)))
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end do
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end do
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end do
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end do
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end if
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end subroutine linear_response_D_pp
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