mirror of
https://github.com/pfloos/quack
synced 2024-12-27 06:43:42 +01:00
77 lines
1.6 KiB
Fortran
77 lines
1.6 KiB
Fortran
|
subroutine W38_lda_correlation_potential(nGrid,weight,nBas,AO,rho,Fc)
|
||
|
|
|
||
|
|
! Compute Wigner's LDA correlation 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,nspin)
|
||
|
|
|
||
|
|
! Local variables
|
||
|
|
|
||
|
|
integer :: mu,nu,iG
|
||
|
|
double precision :: ra,rb,r
|
||
|
|
double precision :: a,d,ec
|
||
|
|
double precision :: dFcdr
|
||
|
|
|
||
|
|
! Output variables
|
||
|
|
|
||
|
|
double precision,intent(out) :: Fc(nBas,nBas,nspin)
|
||
|
|
|
||
|
|
! Coefficients for Wigner's LDA correlation
|
||
|
|
|
||
|
|
a = 0.04918d0
|
||
|
|
d = 0.349d0
|
||
|
|
|
||
|
|
! Compute LDA correlation matrix in the AO basis
|
||
|
|
|
||
|
|
Fc(:,:,:) = 0d0
|
||
|
|
|
||
|
|
do mu=1,nBas
|
||
|
|
do nu=1,nBas
|
||
|
|
do iG=1,nGrid
|
||
|
|
|
||
|
|
ra = max(0d0,rho(iG,1))
|
||
|
|
rb = max(0d0,rho(iG,2))
|
||
|
|
|
||
|
|
! Spin-up part contribution
|
||
|
|
|
||
|
|
if(ra > threshold) then
|
||
|
|
|
||
|
|
r = ra + rb
|
||
|
|
|
||
|
|
ec = ra*rb/(r + d*r**(2d0/3d0))
|
||
|
|
dFcdr = ec*(d/(3d0*r**(4d0/3d0)*(1d0 + d*r**(-1d0/3d0))) - 1d0/r + 1d0/ra)
|
||
|
|
|
||
|
|
Fc(mu,nu,1) = Fc(mu,nu,1) + weight(iG)*AO(mu,iG)*AO(nu,iG)*dFcdr
|
||
|
|
|
||
|
|
endif
|
||
|
|
|
||
|
|
! Spin-down part contribution
|
||
|
|
|
||
|
|
if(rb > threshold) then
|
||
|
|
|
||
|
|
r = ra + rb
|
||
|
|
|
||
|
|
ec = ra*rb/(r + d*r**(2d0/3d0))
|
||
|
|
dFcdr = ec*(d/(3d0*r**(4d0/3d0)*(1d0 + d*r**(-1d0/3d0))) - 1d0/r + 1d0/rb)
|
||
|
|
|
||
|
|
Fc(mu,nu,2) = Fc(mu,nu,2) + weight(iG)*AO(mu,iG)*AO(nu,iG)*dFcdr
|
||
|
|
|
||
|
|
endif
|
||
|
|
|
||
|
|
enddo
|
||
|
|
|
||
|
|
enddo
|
||
|
|
enddo
|
||
|
|
|
||
|
|
Fc(:,:,:) = -4d0*a*Fc(:,:,:)
|
||
|
|
|
||
|
|
end subroutine W38_lda_correlation_potential
|