mirror of
https://github.com/pfloos/quack
synced 2024-06-28 08:02:24 +02:00
81 lines
1.8 KiB
Fortran
81 lines
1.8 KiB
Fortran
subroutine RGIC_lda_exchange_individual_energy(nEns,wEns,nGrid,weight,rhow,rho,Ex)
|
|
|
|
! Compute the restricted version of the GIC exchange functional
|
|
|
|
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)
|
|
double precision,intent(in) :: rho(nGrid)
|
|
|
|
! Local variables
|
|
|
|
integer :: iG
|
|
double precision :: CxGIC
|
|
double precision :: r,rI
|
|
double precision :: e_p,dedr
|
|
|
|
double precision :: a,b,c,w
|
|
|
|
! Output variables
|
|
|
|
double precision,intent(out) :: Ex
|
|
|
|
! Weight-dependent Cx coefficient for RMFL20 exchange functional
|
|
|
|
|
|
! Parameters for H2 at equilibrium
|
|
|
|
! a = + 0.5751782560799208d0
|
|
! b = - 0.021108186591137282d0
|
|
! c = - 0.36718902716347124d0
|
|
|
|
! Parameters for stretch H2
|
|
|
|
! a = + 0.01922622507087411d0
|
|
! b = - 0.01799647558018601d0
|
|
! c = - 0.022945430666782573d0
|
|
|
|
! Parameters for He
|
|
|
|
! a = 1.9125735895875828d0
|
|
! b = 2.715266992840757d0
|
|
! c = 2.1634223380633086d0
|
|
|
|
|
|
! Parameters for HNO
|
|
|
|
a = 0.0061158387543040335d0
|
|
b = -0.00005968703047293955d0
|
|
c = -0.00001692245714408755d0
|
|
|
|
w = wEns(2)
|
|
CxGIC = 1d0 - w*(1d0 - w)*(a + b*(w - 0.5d0) + c*(w - 0.5d0)**2)
|
|
CxGIC = CxLDA*CxGIC
|
|
|
|
! Compute LDA exchange matrix in the AO basis
|
|
|
|
Ex = 0d0
|
|
do iG=1,nGrid
|
|
|
|
r = max(0d0,rhow(iG))
|
|
rI = max(0d0,rho(iG))
|
|
|
|
if(r > threshold .and. rI > threshold) then
|
|
|
|
e_p = CxGIC*r**(1d0/3d0)
|
|
dedr = 1d0/3d0*CxGIC*r**(-2d0/3d0)
|
|
Ex = Ex + weight(iG)*(e_p*rI + dedr*r*rI - dedr*r*r)
|
|
|
|
endif
|
|
|
|
enddo
|
|
|
|
end subroutine RGIC_lda_exchange_individual_energy
|