mirror of https://github.com/pfloos/quack
134 lines
2.8 KiB
Fortran
134 lines
2.8 KiB
Fortran
subroutine static_screening_WD_pp(ispin,eta,nBas,nC,nO,nV,nR,nS,nOO,nVV,lambda,ERI,Omega,rho,WD)
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! Compute the OOOO block of the static screening W for the pp-BSE
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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) :: nS
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integer,intent(in) :: nOO
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integer,intent(in) :: nVV
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double precision,intent(in) :: eta
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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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double precision,intent(in) :: Omega(nS)
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double precision,intent(in) :: rho(nBas,nBas,nS)
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! Local variables
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double precision,external :: Kronecker_delta
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double precision :: chi
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double precision :: eps
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integer :: i,j,k,l,ij,kl,m
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! Output variables
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double precision,intent(out) :: WD(nOO,nOO)
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! Initialization
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WD(:,:) = 0d0
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!---------------!
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! Singlet block !
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!---------------!
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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=i,nO
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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=k,nO
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kl = kl + 1
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chi = 0d0
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do m=1,nS
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eps = Omega(m)**2 + eta**2
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chi = chi + rho(i,k,m)*rho(j,l,m)*Omega(m)/eps &
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+ rho(i,l,m)*rho(j,k,m)*Omega(m)/eps
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enddo
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WD(ij,kl) = + 4d0*lambda*chi/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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!---------------!
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! Triplet block !
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!---------------!
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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=i+1,nO
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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=k+1,nO
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kl = kl + 1
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chi = 0d0
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do m=1,nS
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eps = Omega(m)**2 + eta**2
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chi = chi + rho(i,k,m)*rho(j,l,m)*Omega(m)/eps &
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- rho(i,l,m)*rho(j,k,m)*Omega(m)/eps
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enddo
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WD(ij,kl) = + 4d0*lambda*chi
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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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!---------------!
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! SpinOrb block !
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!---------------!
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if(ispin == 4) then
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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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kl = 0
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do k=nC+1,nO
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do l=k+1,nO
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kl = kl + 1
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chi = 0d0
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do m=1,nS
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eps = Omega(m)**2 + eta**2
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chi = chi + rho(i,k,m)*rho(j,l,m)*Omega(m)/eps &
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- rho(i,l,m)*rho(j,k,m)*Omega(m)/eps
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enddo
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WD(ij,kl) = + 2d0*lambda*chi
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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 static_screening_WD_pp
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