mirror of
https://github.com/pfloos/quack
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106 lines
2.3 KiB
Fortran
106 lines
2.3 KiB
Fortran
subroutine ppLR_C(ispin,nBas,nC,nO,nV,nR,nVV,lambda,e,ERI,Cpp)
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! Compute the C 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) :: nVV
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double precision,intent(in) :: lambda
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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 :: 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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! Define the chemical potential
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! eF = e(nO) + e(nO+1)
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eF = 0d0
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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) = + (e(a) + e(b) - eF)*Kronecker_delta(a,c)*Kronecker_delta(b,d) &
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+ 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) = + (e(a) + e(b) - eF)*Kronecker_delta(a,c)*Kronecker_delta(b,d) &
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+ 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) = + (e(a) + e(b) - eF)*Kronecker_delta(a,c)*Kronecker_delta(b,d) &
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+ 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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