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https://github.com/pfloos/quack
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49 lines
1.0 KiB
Fortran
49 lines
1.0 KiB
Fortran
subroutine density_matrix(nBas,nEns,c,P,occnum)
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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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double precision,intent(in) :: c(nBas,nBas,nspin)
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double precision,intent(in) :: occnum(nBas,nspin,nEns)
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! Local variables
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integer :: ispin
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integer :: iEns
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integer :: q
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integer :: mu,nu
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! Output variables
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double precision,intent(out) :: P(nBas,nBas,nspin,nEns)
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! Compute density matrix for each state of the ensemble based on occupation numbers
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P(:,:,:,:) = 0d0
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do iEns=1,nEns
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do ispin=1,nspin
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do mu=1,nBas
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do nu=1,nBas
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do q=1,nBas
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P(mu,nu,ispin,iEns) = P(mu,nu,ispin,iEns) &
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+ occnum(q,ispin,iEns)*c(mu,q,ispin)*c(nu,q,ispin)
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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 density_matrix
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