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https://github.com/pfloos/quack
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71 lines
1.8 KiB
Fortran
71 lines
1.8 KiB
Fortran
subroutine elda_correlation_potential(aLF,nGrid,weight,nBas,AO,rho,Fc)
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! Compute LDA correlation energy of 2-glomium for various states
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implicit none
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include 'parameters.h'
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! Input variables
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double precision,intent(in) :: aLF(3)
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integer,intent(in) :: nGrid
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double precision,intent(in) :: weight(nGrid)
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integer,intent(in) :: nBas
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double precision,intent(in) :: AO(nBas,nGrid)
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double precision,intent(in) :: rho(nGrid,nspin)
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! Local variables
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integer :: mu,nu,iG
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double precision :: ra,rb,r,ec_p
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double precision :: dFcdra,dFcdrb
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! Output variables
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double precision,intent(out) :: Fc(nBas,nBas,nspin)
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! Compute eLDA correlation potential
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Fc(:,:,:) = 0d0
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do mu=1,nBas
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do nu=1,nBas
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do iG=1,nGrid
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ra = max(0d0,rho(iG,1))
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rb = max(0d0,rho(iG,2))
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if(ra > threshold) then
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r = ra + rb
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ec_p = aLF(1)/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdra = aLF(2)*r**(-1d0/6d0) + 2d0*aLF(3)*r**(-1d0/3d0)
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dFcdra = dFcdra/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdra = ec_p*dFcdra/(6d0*r)
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dFcdra = ec_p + dFcdra*r
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Fc(mu,nu,1) = Fc(mu,nu,1) + weight(iG)*AO(mu,iG)*AO(nu,iG)*dFcdra
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endif
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if(rb > threshold) then
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r = ra + rb
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ec_p = aLF(1)/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdrb = aLF(2)*r**(-1d0/6d0) + 2d0*aLF(3)*r**(-1d0/3d0)
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dFcdrb = dFcdrb/(1d0 + aLF(2)*r**(-1d0/6d0) + aLF(3)*r**(-1d0/3d0))
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dFcdrb = ec_p*dFcdrb/(6d0*r)
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dFcdrb = ec_p + dFcdrb*r
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Fc(mu,nu,2) = Fc(mu,nu,2) + weight(iG)*AO(mu,iG)*AO(nu,iG)*dFcdrb
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endif
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end do
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end do
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end do
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end subroutine elda_correlation_potential
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