mirror of
https://github.com/pfloos/quack
synced 2024-12-25 22:03:44 +01:00
79 lines
2.0 KiB
Fortran
79 lines
2.0 KiB
Fortran
subroutine RVWN5_lda_correlation_potential(nGrid,weight,nBas,AO,rho,Fc)
|
|
|
|
! Compute the restricted VWN5 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)
|
|
|
|
! Local variables
|
|
|
|
integer :: mu,nu,iG
|
|
double precision :: r,rs,x
|
|
double precision :: a_p,x0_p,xx0_p,b_p,c_p,x_p,q_p
|
|
double precision :: dxdrs,dxdx_p,decdx_p
|
|
double precision :: drsdra,decdra_p
|
|
|
|
double precision :: ec_p
|
|
|
|
! Output variables
|
|
|
|
double precision :: Fc(nBas,nBas)
|
|
|
|
! Parameters of the functional
|
|
|
|
a_p = +0.0621814D0/2D0
|
|
x0_p = -0.10498d0
|
|
b_p = +3.72744d0
|
|
c_p = +12.9352d0
|
|
|
|
! Initialization
|
|
|
|
Fc(:,:) = 0d0
|
|
|
|
do mu=1,nBas
|
|
do nu=1,nBas
|
|
do iG=1,nGrid
|
|
|
|
r = max(0d0,rho(iG))
|
|
|
|
if(r > threshold) then
|
|
|
|
rs = (4d0*pi*r/3d0)**(-1d0/3d0)
|
|
x = sqrt(rs)
|
|
|
|
x_p = x*x + b_p*x + c_p
|
|
xx0_p = x0_p*x0_p + b_p*x0_p + c_p
|
|
q_p = sqrt(4d0*c_p - b_p*b_p)
|
|
|
|
ec_p = a_p*( log(x**2/x_p) + 2d0*b_p/q_p*atan(q_p/(2d0*x + b_p)) &
|
|
- b_p*x0_p/xx0_p*( log((x - x0_p)**2/x_p) + 2d0*(b_p + 2d0*x0_p)/q_p*atan(q_p/(2d0*x + b_p)) ) )
|
|
|
|
drsdra = - (36d0*pi)**(-1d0/3d0)*r**(-4d0/3d0)
|
|
dxdrs = 0.5d0/sqrt(rs)
|
|
|
|
dxdx_p = 2d0*x + b_p
|
|
|
|
decdx_p = a_p*( 2d0/x - 4d0*b_p/( (b_p+2d0*x)**2 + q_p**2) - dxdx_p/x_p &
|
|
- b_p*x0_p/xx0_p*( 2/(x-x0_p) - 4d0*(b_p+2d0*x0_p)/( (b_p+2d0*x)**2 + q_p**2) - dxdx_p/x_p ) )
|
|
|
|
decdra_p = drsdra*dxdrs*decdx_p
|
|
|
|
Fc(mu,nu) = Fc(mu,nu) + weight(iG)*AO(mu,iG)*AO(nu,iG)*(ec_p + decdra_p*r)
|
|
|
|
end if
|
|
|
|
end do
|
|
end do
|
|
end do
|
|
|
|
end subroutine RVWN5_lda_correlation_potential
|