mirror of
https://github.com/pfloos/quack
synced 2024-06-25 22:52:18 +02:00
162 lines
4.7 KiB
Fortran
162 lines
4.7 KiB
Fortran
subroutine G0F2(BSE,TDA,singlet_manifold,triplet_manifold,linearize,eta,nBas,nC,nO,nV,nR,nS,ENuc,ERHF,ERI,eHF)
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! Perform a one-shot second-order Green function calculation
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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) :: BSE
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logical,intent(in) :: TDA
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logical,intent(in) :: singlet_manifold
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logical,intent(in) :: triplet_manifold
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logical,intent(in) :: linearize
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double precision,intent(in) :: eta
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integer,intent(in) :: nBas
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integer,intent(in) :: nO
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integer,intent(in) :: nC
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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) :: ENuc
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double precision,intent(in) :: ERHF
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double precision,intent(in) :: eHF(nBas)
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double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas)
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! Local variables
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double precision :: eps
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double precision :: V
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double precision :: EcBSE(nspin)
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double precision,allocatable :: eGF2(:)
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double precision,allocatable :: Sig(:)
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double precision,allocatable :: Z(:)
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integer :: i,j,a,b,p
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! Hello world
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write(*,*)
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write(*,*)'************************************************'
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write(*,*)'| One-shot second-order Green function |'
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write(*,*)'************************************************'
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write(*,*)
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! Memory allocation
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allocate(Sig(nBas),Z(nBas),eGF2(nBas))
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if(linearize) then
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write(*,*) '*** Quasiparticle equation will be linearized ***'
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write(*,*)
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end if
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! Frequency-dependent second-order contribution
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Sig(:) = 0d0
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Z(:) = 0d0
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do p=nC+1,nBas-nR
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do i=nC+1,nO
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do j=nC+1,nO
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do a=nO+1,nBas-nR
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eps = eHF(p) + eHF(a) - eHF(i) - eHF(j)
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V = (2d0*ERI(p,a,i,j) - ERI(p,a,j,i))*ERI(p,a,i,j)
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Sig(p) = Sig(p) + V*eps/(eps**2 + eta**2)
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Z(p) = Z(p) - V*(eps**2 - eta**2)/(eps**2 + eta**2)**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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do p=nC+1,nBas-nR
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do i=nC+1,nO
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do a=nO+1,nBas-nR
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do b=nO+1,nBas-nR
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eps = eHF(p) + eHF(i) - eHF(a) - eHF(b)
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V = (2d0*ERI(p,i,a,b) - ERI(p,i,b,a))*ERI(p,i,a,b)
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Sig(p) = Sig(p) + V*eps/(eps**2 + eta**2)
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Z(p) = Z(p) - V*(eps**2 - eta**2)/(eps**2 + eta**2)**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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Z(:) = 1d0/(1d0 - Z(:))
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if(linearize) then
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eGF2(:) = eHF(:) + Z(:)*Sig(:)
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else
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eGF2(:) = eHF(:) + Sig(:)
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end if
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! Print results
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call print_G0F2(nBas,nO,eHF,Sig,eGF2,Z)
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! Perform BSE2 calculation
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if(BSE) then
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call BSE2(TDA,singlet_manifold,triplet_manifold,eta,nBas,nC,nO,nV,nR,nS,ERI,eHF,eGF2,EcBSE)
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write(*,*)
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write(*,*)'-------------------------------------------------------------------------------'
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write(*,'(2X,A50,F20.10)') 'Tr@BSE2@G0F correlation energy (singlet) =',EcBSE(1)
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write(*,'(2X,A50,F20.10)') 'Tr@BSE2@G0F correlation energy (triplet) =',EcBSE(2)
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write(*,'(2X,A50,F20.10)') 'Tr@BSE2@G0F correlation energy =',EcBSE(1) + EcBSE(2)
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write(*,'(2X,A50,F20.10)') 'Tr@BSE2@G0F total energy =',ENuc + ERHF + EcBSE(1) + EcBSE(2)
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write(*,*)'-------------------------------------------------------------------------------'
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write(*,*)
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! Compute the BSE correlation energy via the adiabatic connection
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! if(doACFDT) then
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! write(*,*) '------------------------------------------------------'
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! write(*,*) 'Adiabatic connection version of BSE correlation energy'
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! write(*,*) '------------------------------------------------------'
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! write(*,*)
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! if(doXBS) then
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! write(*,*) '*** scaled screening version (XBS) ***'
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! write(*,*)
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! end if
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! call ACFDT(exchange_kernel,doXBS,.true.,TDA,BSE,singlet_manifold,triplet_manifold,eta, &
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! nBas,nC,nO,nV,nR,nS,ERI,eHF,eGW,Omega,XpY,XmY,rho,EcAC)
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! if(exchange_kernel) then
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!
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! EcAC(1) = 0.5d0*EcAC(1)
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! EcAC(2) = 1.5d0*EcAC(1)
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!
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! end if
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! write(*,*)
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! write(*,*)'-------------------------------------------------------------------------------'
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! write(*,'(2X,A50,F20.10)') 'AC@BSE@G0W0 correlation energy (singlet) =',EcAC(1)
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! write(*,'(2X,A50,F20.10)') 'AC@BSE@G0W0 correlation energy (triplet) =',EcAC(2)
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! write(*,'(2X,A50,F20.10)') 'AC@BSE@G0W0 correlation energy =',EcAC(1) + EcAC(2)
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! write(*,'(2X,A50,F20.10)') 'AC@BSE@G0W0 total energy =',ENuc + ERHF + EcAC(1) + EcAC(2)
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! write(*,*)'-------------------------------------------------------------------------------'
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! write(*,*)
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! end if
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end if
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end subroutine G0F2
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