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60 lines
1.4 KiB
Fortran
60 lines
1.4 KiB
Fortran
subroutine RMFL20_lda_correlation_derivative_discontinuity(nEns,wEns,nGrid,weight,rhow,EcDD)
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! Compute the restricted version of the eLDA correlation part of the derivative discontinuity
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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) :: nEns
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double precision,intent(in) :: wEns(nEns)
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integer,intent(in) :: nGrid
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double precision,intent(in) :: weight(nGrid)
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double precision,intent(in) :: rhow(nGrid)
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! Local variables
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integer :: iEns,jEns
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double precision,allocatable :: aMFL(:,:)
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double precision :: dEcdw(nEns)
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double precision,external :: Kronecker_delta
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! Output variables
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double precision,intent(out) :: EcDD(nEns)
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! Allocation
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allocate(aMFL(3,nEns))
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! Parameters for weight-dependent LDA correlation functional
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aMFL(1,1) = -0.0238184d0
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aMFL(2,1) = +0.00540994d0
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aMFL(3,1) = +0.0830766d0
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aMFL(1,2) = -0.0144633d0
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aMFL(2,2) = -0.0506019d0
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aMFL(3,2) = +0.0331417d0
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! Compute correlation energy for ground, singly-excited and doubly-excited states
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do iEns=1,nEns
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call restricted_elda_correlation_energy(nEns,aMFL(:,iEns),nGrid,weight(:),rhow(:),dEcdw(iEns))
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end do
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EcDD(:) = 0d0
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do iEns=1,nEns
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do jEns=1,nEns
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EcDD(iEns) = EcDD(iEns) + (Kronecker_delta(iEns,jEns) - wEns(jEns))*(dEcdw(jEns) - dEcdw(1))
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end do
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end do
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end subroutine RMFL20_lda_correlation_derivative_discontinuity
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