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quack/src/eDFT/US51_lda_exchange_potential.f90

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subroutine US51_lda_exchange_potential(nGrid,weight,nBas,AO,rho,Fx)
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! Compute Slater's LDA exchange potential
implicit none
include 'parameters.h'
! Input variables
integer,intent(in) :: nGrid
double precision,intent(in) :: weight(nGrid)
integer,intent(in) :: nBas
double precision,intent(in) :: AO(nBas,nGrid)
double precision,intent(in) :: rho(nGrid)
! Local variables
integer :: mu,nu,iG
double precision :: r,vAO
! Output variables
double precision,intent(out) :: Fx(nBas,nBas)
! Compute LDA exchange matrix in the AO basis
Fx(:,:) = 0d0
do mu=1,nBas
do nu=1,nBas
do iG=1,nGrid
r = max(0d0,rho(iG))
if(r > threshold) then
vAO = weight(iG)*AO(mu,iG)*AO(nu,iG)
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Fx(mu,nu) = Fx(mu,nu) + vAO*4d0/3d0*CxLSDA*r**(1d0/3d0)
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endif
enddo
enddo
enddo
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end subroutine US51_lda_exchange_potential