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https://github.com/pfloos/quack
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59 lines
1.5 KiB
Fortran
59 lines
1.5 KiB
Fortran
subroutine RMFL20_lda_exchange_individual_energy(LDA_centered,nEns,wEns,nGrid,weight,rhow,rho,Ex)
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! Compute the restricted version of the Marut-Fromager-Loos 2020 weight-dependent exchange functional
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implicit none
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include 'parameters.h'
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! Input variables
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logical,intent(in) :: LDA_centered
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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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double precision,intent(in) :: rho(nGrid)
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! Local variables
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integer :: iG
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double precision :: Cxw
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double precision :: r,rI
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double precision :: e_p,dedr
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double precision,parameter :: Cx0 = - (4d0/3d0)*(1d0/pi)**(1d0/3d0)
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double precision,parameter :: Cx1 = - (176d0/105d0)*(1d0/pi)**(1d0/3d0)
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! Output variables
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double precision,intent(out) :: Ex
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! Weight-dependent Cx coefficient for RMFL20 exchange functional
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if(LDA_centered) then
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Cxw = CxLDA + (Cx1 - Cx0)*wEns(2)
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else
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Cxw = wEns(1)*Cx0 + wEns(2)*Cx1
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end if
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! Compute LDA exchange matrix in the AO basis
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Ex = 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 .or. rI > threshold) then
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e_p = Cxw*r**(1d0/3d0)
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dedr = 1d0/3d0*Cxw*r**(-2d0/3d0)
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Ex = Ex + weight(iG)*(e_p*rI + dedr*r*rI - dedr*r*r)
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endif
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enddo
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end subroutine RMFL20_lda_exchange_individual_energy
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