mirror of
https://github.com/pfloos/quack
synced 2024-08-16 17:48:35 +02:00
59 lines
1.4 KiB
Fortran
59 lines
1.4 KiB
Fortran
subroutine RMFL20_lda_exchange_derivative_discontinuity(nEns,wEns,nGrid,weight,rhow,ExDD)
|
|
|
|
! Compute the restricted version of the eLDA exchange part of the derivative discontinuity
|
|
|
|
implicit none
|
|
include 'parameters.h'
|
|
|
|
! Input variables
|
|
|
|
integer,intent(in) :: nEns
|
|
double precision,intent(in) :: wEns(nEns)
|
|
integer,intent(in) :: nGrid
|
|
double precision,intent(in) :: weight(nGrid)
|
|
double precision,intent(in) :: rhow(nGrid)
|
|
|
|
! Local variables
|
|
|
|
integer :: iEns,jEns
|
|
integer :: iG
|
|
double precision :: r
|
|
double precision :: dExdw(nEns)
|
|
double precision,external :: Kronecker_delta
|
|
|
|
double precision,parameter :: Cx0 = - (4d0/3d0)*(1d0/pi)**(1d0/3d0)
|
|
double precision,parameter :: Cx1 = - (176d0/105d0)*(1d0/pi)**(1d0/3d0)
|
|
|
|
! Output variables
|
|
|
|
double precision,intent(out) :: ExDD(nEns)
|
|
|
|
! Compute correlation energy for ground- and doubly-excited states
|
|
|
|
dExdw(:) = 0d0
|
|
|
|
do iG=1,nGrid
|
|
|
|
r = max(0d0,rhow(iG))
|
|
|
|
if(r > threshold) then
|
|
|
|
dExdw(1) = 0d0
|
|
dExdw(2) = dExdw(2) + weight(iG)*(Cx1 - Cx0)*r**(4d0/3d0)
|
|
|
|
end if
|
|
|
|
end do
|
|
|
|
ExDD(:) = 0d0
|
|
|
|
do iEns=1,nEns
|
|
do jEns=2,nEns
|
|
|
|
ExDD(iEns) = ExDD(iEns) + (Kronecker_delta(iEns,jEns) - wEns(jEns))*dExdw(jEns)
|
|
|
|
end do
|
|
end do
|
|
|
|
end subroutine RMFL20_lda_exchange_derivative_discontinuity
|