mirror of
https://github.com/pfloos/quack
synced 2024-12-25 22:03:44 +01:00
86 lines
1.9 KiB
Fortran
86 lines
1.9 KiB
Fortran
subroutine RGIC_lda_exchange_derivative_discontinuity(nEns,wEns,nGrid,weight,rhow,ExDD)
|
|
|
|
! Compute the restricted version of the GIC exchange individual energy
|
|
|
|
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,allocatable :: dExdw(:)
|
|
double precision,external :: Kronecker_delta
|
|
|
|
double precision :: a,b,c,w
|
|
double precision :: dCxGICdw
|
|
|
|
! Output variables
|
|
|
|
double precision,intent(out) :: ExDD(nEns)
|
|
|
|
! Memory allocation
|
|
|
|
allocate(dExdw(nEns))
|
|
|
|
! Weight-dependent Cx coefficient for RMFL20 exchange functional
|
|
|
|
! Parameters for H2 at equilibrium
|
|
|
|
a = + 0.5739189000851961d0
|
|
b = - 0.0003469882157336496d0
|
|
c = - 0.2676338054343272d0
|
|
|
|
! Parameters for stretch H2
|
|
|
|
! a = + 0.01918229168254928d0
|
|
! b = - 0.01545313842512261d0
|
|
! c = - 0.012720073519142448d0
|
|
|
|
! Parameters for He
|
|
|
|
! a = 1.9015719148496788d0
|
|
! b = 2.5236598782764412d0
|
|
! c = 1.6652282199359842d0
|
|
|
|
w = 0.5d0*wEns(2) + wEns(3)
|
|
dCxGICdw = (0.5d0*b + (2d0*a + 0.5d0*c)*(w - 0.5d0) - (1d0 - w)*w*(3d0*b + 4d0*c*(w - 0.5d0)))
|
|
dCxGICdw = CxLDA*dCxGICdw
|
|
|
|
dExdw(:) = 0d0
|
|
|
|
do iG=1,nGrid
|
|
|
|
r = max(0d0,rhow(iG))
|
|
|
|
if(r > threshold) then
|
|
|
|
dExdw(1) = 0d0
|
|
dExdw(2) = dExdw(2) + 0.5d0*weight(iG)*dCxGICdw*r**(4d0/3d0)
|
|
dExdw(3) = dExdw(3) + 1.0d0*weight(iG)*dCxGICdw*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 RGIC_lda_exchange_derivative_discontinuity
|