mirror of
https://github.com/pfloos/quack
synced 2025-01-09 12:44:04 +01:00
133 lines
2.8 KiB
Fortran
133 lines
2.8 KiB
Fortran
subroutine GW_ppBSE_static_kernel_C(ispin,eta,nBas,nC,nO,nV,nR,nS,nVV,lambda,ERI,Om,rho,KC)
|
|
|
|
! Compute the VVVV block of the static screening W for the pp-BSE
|
|
|
|
implicit none
|
|
include 'parameters.h'
|
|
|
|
! Input variables
|
|
|
|
integer,intent(in) :: ispin
|
|
integer,intent(in) :: nBas
|
|
integer,intent(in) :: nC
|
|
integer,intent(in) :: nO
|
|
integer,intent(in) :: nV
|
|
integer,intent(in) :: nR
|
|
integer,intent(in) :: nS
|
|
integer,intent(in) :: nVV
|
|
double precision,intent(in) :: eta
|
|
double precision,intent(in) :: lambda
|
|
double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas)
|
|
double precision,intent(in) :: Om(nS)
|
|
double precision,intent(in) :: rho(nBas,nBas,nS)
|
|
|
|
! Local variables
|
|
|
|
double precision,external :: Kronecker_delta
|
|
double precision :: chi
|
|
double precision :: eps
|
|
integer :: a,b,c,d,ab,cd,m
|
|
|
|
! Output variables
|
|
|
|
double precision,intent(out) :: KC(nVV,nVV)
|
|
|
|
! Initialization
|
|
|
|
KC(:,:) = 0d0
|
|
|
|
!---------------!
|
|
! Singlet block !
|
|
!---------------!
|
|
|
|
if(ispin == 1) then
|
|
|
|
ab = 0
|
|
do a=nO+1,nBas-nR
|
|
do b=a,nBas-nR
|
|
ab = ab + 1
|
|
cd = 0
|
|
do c=nO+1,nBas-nR
|
|
do d=c,nBas-nR
|
|
cd = cd + 1
|
|
|
|
chi = 0d0
|
|
do m=1,nS
|
|
eps = Om(m)**2 + eta**2
|
|
chi = chi - rho(a,c,m)*rho(b,d,m)*Om(m)/eps &
|
|
+ rho(a,d,m)*rho(b,c,m)*Om(m)/eps
|
|
enddo
|
|
|
|
KC(ab,cd) = 2d0*lambda*chi/sqrt((1d0 + Kronecker_delta(a,b))*(1d0 + Kronecker_delta(c,d)))
|
|
|
|
end do
|
|
end do
|
|
end do
|
|
end do
|
|
|
|
end if
|
|
|
|
!---------------!
|
|
! Triplet block !
|
|
!---------------!
|
|
|
|
if(ispin == 2) then
|
|
|
|
ab = 0
|
|
do a=nO+1,nBas-nR
|
|
do b=a+1,nBas-nR
|
|
ab = ab + 1
|
|
cd = 0
|
|
do c=nO+1,nBas-nR
|
|
do d=c+1,nBas-nR
|
|
cd = cd + 1
|
|
|
|
chi = 0d0
|
|
do m=1,nS
|
|
eps = Om(m)**2 + eta**2
|
|
chi = chi - rho(a,c,m)*rho(b,d,m)*Om(m)/eps &
|
|
+ rho(a,d,m)*rho(b,c,m)*Om(m)/eps
|
|
enddo
|
|
|
|
KC(ab,cd) = 2d0*lambda*chi
|
|
|
|
end do
|
|
end do
|
|
end do
|
|
end do
|
|
|
|
end if
|
|
|
|
!---------------!
|
|
! SpinOrb block !
|
|
!---------------!
|
|
|
|
if(ispin == 4) then
|
|
|
|
ab = 0
|
|
do a=nO+1,nBas-nR
|
|
do b=a+1,nBas-nR
|
|
ab = ab + 1
|
|
cd = 0
|
|
do c=nO+1,nBas-nR
|
|
do d=c+1,nBas-nR
|
|
cd = cd + 1
|
|
|
|
chi = 0d0
|
|
do m=1,nS
|
|
eps = Om(m)**2 + eta**2
|
|
chi = chi - rho(a,c,m)*rho(b,d,m)*Om(m)/eps &
|
|
+ rho(a,d,m)*rho(b,c,m)*Om(m)/eps
|
|
enddo
|
|
|
|
KC(ab,cd) = lambda*chi
|
|
|
|
end do
|
|
end do
|
|
end do
|
|
end do
|
|
|
|
end if
|
|
|
|
end subroutine
|