mirror of
https://github.com/pfloos/quack
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124 lines
2.7 KiB
Fortran
124 lines
2.7 KiB
Fortran
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subroutine BSE2_static_kernel(eta,nBas,nC,nO,nV,nR,nS,lambda,eW,ERI,Om,rho,A_sta)
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! Compute the second-order static BSE kernel (only for singlets!)
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implicit none
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include 'parameters.h'
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! Input variables
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double precision,intent(in) :: eta
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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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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) :: eW(nBas)
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double precision,intent(in) :: Om(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 :: chi
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integer :: p,q,r,s
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integer :: m
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double precision :: dem,num
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integer :: i,j,k,l
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integer :: a,b,c,d
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integer :: ia,jb
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double precision,allocatable :: W(:,:,:,:)
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! Output variables
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double precision,intent(inout) :: A_sta(nS,nS)
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! memory allocation
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allocate(W(nBas,nBas,nBas,nBas))
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!------------------------------------------------
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! Compute static screening (physicist's notation)
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!------------------------------------------------
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do p=1,nBas
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do q=1,nBas
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do r=1,nBas
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do s=1,nBas
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chi = 0d0
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do m=1,nS
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dem = Om(m)**2 + eta**2
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chi = chi + rho(p,q,m)*rho(r,s,m)*Om(m)/dem
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enddo
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W(p,s,q,r) = - ERI(p,s,q,r) + 4d0*chi
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enddo
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enddo
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enddo
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enddo
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ia = 0
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do i=nC+1,nO
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do a=nO+1,nBas-nR
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ia = ia + 1
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jb = 0
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do j=nC+1,nO
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do b=nO+1,nBas-nR
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jb = jb + 1
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do k=nC+1,nO
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do c=nO+1,nBas-nR
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dem = - (eW(c) - eW(k))
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num = 2d0*W(j,k,i,c)*W(a,c,b,k)
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A_sta(ia,jb) = A_sta(ia,jb) - num*dem/(dem**2 + eta**2)
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dem = + (eW(c) - eW(k))
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num = 2d0*W(j,c,i,k)*W(a,k,b,c)
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A_sta(ia,jb) = A_sta(ia,jb) + num*dem/(dem**2 + eta**2)
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end do
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end do
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do c=nO+1,nBas-nR
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do d=nO+1,nBas-nR
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dem = - (eW(c) + eW(d))
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num = 2d0*W(a,j,c,d)*W(c,d,i,b)
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A_sta(ia,jb) = A_sta(ia,jb) + num*dem/(dem**2 + eta**2)
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end do
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end do
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do k=nC+1,nO
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do l=nC+1,nO
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dem = - (eW(k) + eW(l))
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num = 2d0*W(a,j,k,l)*W(k,l,i,b)
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A_sta(ia,jb) = A_sta(ia,jb) - num*dem/(dem**2 + eta**2)
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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 do
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end do
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end subroutine BSE2_static_kernel
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