mirror of https://github.com/pfloos/quack
92 lines
1.8 KiB
Fortran
92 lines
1.8 KiB
Fortran
subroutine ppLR_C_od(ispin,nBas,nC,nO,nV,nR,nOO,nVV,lambda,ERI,Cpp)
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! Compute the C matrix of the pp channel (without diagonal term)
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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) :: 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,c,d,ab,cd
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! Output variables
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double precision,intent(out) :: Cpp(nVV,nVV)
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! Build C 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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cd = 0
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do c=nO+1,nBas-nR
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do d=c,nBas-nR
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cd = cd + 1
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Cpp(ab,cd) = lambda*(ERI(a,b,c,d) + ERI(a,b,d,c))/sqrt((1d0 + Kronecker_delta(a,b))*(1d0 + Kronecker_delta(c,d)))
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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 C matrix for the triplet manifold, or alpha-alpha block, 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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cd = 0
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do c=nO+1,nBas-nR
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do d=c+1,nBas-nR
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cd = cd + 1
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Cpp(ab,cd) = lambda*(ERI(a,b,c,d) - ERI(a,b,d,c))
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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 C 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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cd = 0
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do c=nO+1,nBas-nR
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do d=nO+1,nBas-nR
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cd = cd + 1
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Cpp(ab,cd) = lambda*ERI(a,b,c,d)
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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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