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https://github.com/pfloos/quack
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51 lines
1.1 KiB
Fortran
51 lines
1.1 KiB
Fortran
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subroutine S51_lda_exchange_potential(nGrid,weight,nBas,AO,rho,Fx)
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! Compute Slater's LDA exchange potential
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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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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)
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! Local variables
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integer :: mu,nu,iG
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double precision :: alpha
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double precision :: r,vAO
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! Output variables
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double precision,intent(out) :: Fx(nBas,nBas)
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! Cx coefficient for Slater LDA exchange
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alpha = -(3d0/2d0)*(3d0/(4d0*pi))**(1d0/3d0)
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! Compute LDA exchange matrix in the AO basis
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Fx(:,:) = 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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r = max(0d0,rho(iG))
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if(r > threshold) then
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vAO = weight(iG)*AO(mu,iG)*AO(nu,iG)
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Fx(mu,nu) = Fx(mu,nu) + vAO*4d0/3d0*alpha*r**(1d0/3d0)
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endif
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enddo
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enddo
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enddo
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end subroutine S51_lda_exchange_potential
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