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https://github.com/pfloos/quack
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57 lines
1.2 KiB
Fortran
57 lines
1.2 KiB
Fortran
subroutine linear_response_B_pp(ispin,dRPA,nBas,nC,nO,nV,nR,nOO,nVV,e,ERI,B_pp)
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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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logical,intent(in) :: dRPA
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integer,intent(in) :: nBas,nC,nO,nV,nR,nOO,nVV
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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 :: delta_spin
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double precision :: delta_dRPA
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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) :: B_pp(nVV,nOO)
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! Singlet or triplet manifold?
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delta_spin = 0d0
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if(ispin == 1) delta_spin = +1d0
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if(ispin == 2) delta_spin = -1d0
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! Direct RPA
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delta_dRPA = 0d0
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if(dRPA) delta_dRPA = 1d0
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! Build A matrix
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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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B_pp(ab,ij) = (1d0 + delta_spin)*ERI(a,b,i,j) - (1d0 - delta_dRPA)*ERI(a,b,j,j)
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enddo
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enddo
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enddo
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enddo
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end subroutine linear_response_B_pp
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