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https://github.com/pfloos/quack
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44 lines
1.1 KiB
Fortran
44 lines
1.1 KiB
Fortran
subroutine density_matrix(nBas,nEns,nO,c,P)
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! Calculate density matrices
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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) :: nBas
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integer,intent(in) :: nEns
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integer,intent(in) :: nO(nspin)
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double precision,intent(in) :: c(nBas,nBas,nspin)
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! Local variables
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integer :: ispin
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! Output variables
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double precision,intent(out) :: P(nBas,nBas,nspin,nEns)
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! Ground state density matrix
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do ispin=1,nspin
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P(:,:,ispin,1) = matmul(c(:,1:nO(ispin),ispin),transpose(c(:,1:nO(ispin),ispin)))
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end do
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! Singly-excited state density matrix
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P(:,:,1,2) = matmul(c(:,1:nO(1)-1,1),transpose(c(:,1:nO(1)-1,1))) &
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+ matmul(c(:,nO(1)+1:nO(1)+1,1),transpose(c(:,nO(1)+1:nO(1)+1,1)))
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P(:,:,2,2) = matmul(c(:,1:nO(2),2),transpose(c(:,1:nO(2),2)))
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! Doubly-excited state density matrix
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do ispin=1,nspin
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P(:,:,ispin,3) = matmul(c(:,1:nO(ispin)-1,ispin),transpose(c(:,1:nO(ispin)-1,ispin))) &
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+ matmul(c(:,nO(ispin)+1:nO(ispin)+1,ispin),transpose(c(:,nO(ispin)+1:nO(ispin)+1,ispin)))
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end do
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end subroutine density_matrix
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