mirror of
https://github.com/pfloos/quack
synced 2024-09-06 19:54:45 +02:00
48 lines
1.0 KiB
Fortran
48 lines
1.0 KiB
Fortran
![]() |
subroutine US51_lda_exchange_individual_energy(nGrid,weight,rhow,rho,Ex)
|
||
|
|
||
|
! Compute the restricted version of Slater's LDA exchange individual energy
|
||
|
|
||
|
implicit none
|
||
|
include 'parameters.h'
|
||
|
|
||
|
! Input variables
|
||
|
|
||
|
integer,intent(in) :: nGrid
|
||
|
double precision,intent(in) :: weight(nGrid)
|
||
|
double precision,intent(in) :: rhow(nGrid)
|
||
|
double precision,intent(in) :: rho(nGrid)
|
||
|
|
||
|
! Local variables
|
||
|
|
||
|
integer :: iG
|
||
|
double precision :: r,rI,alpha
|
||
|
double precision :: e,dedr
|
||
|
|
||
|
! Output variables
|
||
|
|
||
|
double precision,intent(out) :: Ex
|
||
|
|
||
|
! Compute LDA exchange matrix in the AO basis
|
||
|
|
||
|
alpha = -(3d0/2d0)*(3d0/(4d0*pi))**(1d0/3d0)
|
||
|
|
||
|
|
||
|
Ex = 0d0
|
||
|
do iG=1,nGrid
|
||
|
|
||
|
r = max(0d0,rhow(iG))
|
||
|
rI = max(0d0,rho(iG))
|
||
|
|
||
|
if(r > threshold .or. rI > threshold) then
|
||
|
|
||
|
e = alpha*r**(1d0/3d0)
|
||
|
dedr = 1d0/3d0*alpha*r**(-2d0/3d0)
|
||
|
|
||
|
Ex = Ex + weight(iG)*(e*rI + dedr*r*rI - dedr*r*r)
|
||
|
|
||
|
endif
|
||
|
|
||
|
enddo
|
||
|
|
||
|
end subroutine US51_lda_exchange_individual_energy
|