mirror of https://github.com/pfloos/quack
97 lines
1.9 KiB
Fortran
97 lines
1.9 KiB
Fortran
subroutine ppLR_B(ispin,nBas,nC,nO,nV,nR,nOO,nVV,lambda,ERI,Bpp)
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! Compute the B 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
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integer,intent(in) :: nC
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integer,intent(in) :: nO
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integer,intent(in) :: nV
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integer,intent(in) :: nR
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integer,intent(in) :: nOO
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integer,intent(in) :: nVV
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double precision,intent(in) :: lambda
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double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas)
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! Local variables
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double precision,external :: Kronecker_delta
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integer :: a,b,i,j,ab,ij
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! Output variables
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double precision,intent(out) :: Bpp(nVV,nOO)
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! Build B matrix for the singlet manifold
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if(ispin == 1) then
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ab = 0
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do a=nO+1,nBas-nR
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do b=a,nBas-nR
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ab = ab + 1
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ij = 0
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do i=nC+1,nO
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do j=i,nO
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ij = ij + 1
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Bpp(ab,ij) = lambda*(ERI(a,b,i,j) + ERI(a,b,j,i))/sqrt((1d0 + Kronecker_delta(a,b))*(1d0 + Kronecker_delta(i,j)))
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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 B matrix for the triplet manifold, or alpha-alpha, or in the spin-orbital basis
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if(ispin == 2 .or. ispin == 4) then
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ab = 0
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do a=nO+1,nBas-nR
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do b=a+1,nBas-nR
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ab = ab + 1
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ij = 0
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do i=nC+1,nO
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do j=i+1,nO
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ij = ij + 1
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Bpp(ab,ij) = lambda*(ERI(a,b,i,j) - ERI(a,b,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 alpha-beta block of the B matrix
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if(ispin == 3) then
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ab = 0
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do a=nO+1,nBas-nR
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do b=nO+1,nBas-nR
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ab = ab + 1
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ij = 0
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do i=nC+1,nO
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do j=nC+1,nO
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ij = ij + 1
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Bpp(ab,ij) = lambda*ERI(a,b,i,j)
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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
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