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https://github.com/pfloos/quack
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63 lines
1.3 KiB
Fortran
63 lines
1.3 KiB
Fortran
subroutine US51_lda_exchange_individual_energy(nGrid,weight,rhow,rho,doNcentered,kappa,Ex)
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! Compute the restricted version of Slater's LDA exchange individual energy
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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) :: 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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double precision,intent(in) :: rho(nGrid)
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logical,intent(in) :: doNcentered
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double precision,intent(in) :: kappa
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! Local variables
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integer :: iG
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double precision :: r,rI
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double precision :: e,dedr
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double precision :: Exrr,ExrI,ExrrI
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! Output variables
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double precision,intent(out) :: Ex
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! Compute LDA exchange matrix in the AO basis
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Exrr = 0d0
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ExrI = 0d0
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ExrrI = 0d0
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do iG=1,nGrid
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r = max(0d0,rhow(iG))
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rI = max(0d0,rho(iG))
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if(r > threshold) then
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e = CxLSDA*r**(1d0/3d0)
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dedr = 1d0/3d0*CxLSDA*r**(-2d0/3d0)
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Exrr = Exrr - weight(iG)*dedr*r*r
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if(rI > threshold) then
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ExrI = ExrI + weight(iG)*e*rI
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ExrrI = ExrrI + weight(iG)*dedr*r*rI
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endif
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endif
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enddo
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Exrr = kappa*Exrr
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ExrI = kappa*ExrI
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Ex = Exrr + ExrI + ExrrI
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end subroutine US51_lda_exchange_individual_energy
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