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https://github.com/pfloos/quack
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120 lines
2.7 KiB
Fortran
120 lines
2.7 KiB
Fortran
subroutine self_energy_correlation(COHSEX,eta,nBas,nC,nO,nV,nR,nS,e,Omega,rho,EcGM,SigC)
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! Compute correlation part of the self-energy
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implicit none
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include 'parameters.h'
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! Input variables
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logical,intent(in) :: COHSEX
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double precision,intent(in) :: eta
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integer,intent(in) :: nBas
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integer,intent(in) :: nC
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integer,intent(in) :: nO
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integer,intent(in) :: nV
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integer,intent(in) :: nR
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integer,intent(in) :: nS
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double precision,intent(in) :: e(nBas)
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double precision,intent(in) :: Omega(nS)
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double precision,intent(in) :: rho(nBas,nBas,nS)
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! Local variables
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integer :: i,j,a,b
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integer :: p,q,r
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integer :: jb
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double precision :: eps
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! Output variables
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double precision,intent(out) :: EcGM
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double precision,intent(out) :: SigC(nBas,nBas)
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! Initialize
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SigC(:,:) = 0d0
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!-----------------------------!
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! COHSEX static approximation !
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!-----------------------------!
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if(COHSEX) then
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! COHSEX: SEX of the COHSEX correlation self-energy
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do p=nC+1,nBas-nR
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do q=nC+1,nBas-nR
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do i=nC+1,nO
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do jb=1,nS
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SigC(p,q) = SigC(p,q) + 4d0*rho(p,i,jb)*rho(q,i,jb)/Omega(jb)
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end do
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end do
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end do
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end do
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! COHSEX: COH part of the COHSEX correlation self-energy
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do p=nC+1,nBas-nR
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do q=nC+1,nBas-nR
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do r=nC+1,nBas-nR
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do jb=1,nS
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SigC(p,q) = SigC(p,q) - 2d0*rho(p,r,jb)*rho(q,r,jb)/Omega(jb)
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end do
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end do
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end do
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end do
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EcGM = 0d0
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do i=nC+1,nO
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EcGM = EcGM + 0.5d0*SigC(i,i)
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end do
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else
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!----------------!
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! GW self-energy !
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!----------------!
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! Occupied part of the correlation self-energy
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do p=nC+1,nBas-nR
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do q=nC+1,nBas-nR
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do i=nC+1,nO
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do jb=1,nS
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eps = e(p) - e(i) + Omega(jb)
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SigC(p,q) = SigC(p,q) + 2d0*rho(p,i,jb)*rho(q,i,jb)*eps/(eps**2 + eta**2)
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end do
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end do
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end do
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end do
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! Virtual part of the correlation self-energy
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do p=nC+1,nBas-nR
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do q=nC+1,nBas-nR
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do a=nO+1,nBas-nR
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do jb=1,nS
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eps = e(p) - e(a) - Omega(jb)
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SigC(p,q) = SigC(p,q) + 2d0*rho(p,a,jb)*rho(q,a,jb)*eps/(eps**2 + eta**2)
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end do
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end do
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end do
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end do
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! Galitskii-Migdal correlation energy
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EcGM = 0d0
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do i=nC+1,nO
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do a=nO+1,nBas-nR
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do jb=1,nS
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eps = e(a) - e(i) + Omega(jb)
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EcGM = EcGM - 4d0*rho(a,i,jb)*rho(a,i,jb)*eps/(eps**2 + eta**2)
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end do
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end do
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end do
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end if
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end subroutine self_energy_correlation
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