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https://github.com/pfloos/quack
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181 lines
4.2 KiB
Fortran
181 lines
4.2 KiB
Fortran
subroutine GF2_diag(maxSCF,thresh,max_diis,linearize,nBas,nC,nO,nV,nR,V,e0)
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! Perform second-order Green function calculation in diagonal approximation
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implicit none
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include 'parameters.h'
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! Input variables
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integer,intent(in) :: maxSCF
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double precision,intent(in) :: thresh
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integer,intent(in) :: max_diis
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logical,intent(in) :: linearize
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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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double precision,intent(in) :: e0(nBas)
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double precision,intent(in) :: V(nBas,nBas,nBas,nBas)
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! Local variables
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integer :: nSCF
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integer :: n_diis
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double precision :: eps
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double precision :: Conv
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double precision :: rcond
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double precision,allocatable :: eGF2(:)
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double precision,allocatable :: eOld(:)
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double precision,allocatable :: Bpp(:,:)
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double precision,allocatable :: Z(:)
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double precision,allocatable :: error_diis(:,:)
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double precision,allocatable :: e_diis(:,:)
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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(*,*)'| Second-order Green function calculation |'
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write(*,*)'************************************************'
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write(*,*)
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! Memory allocation
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allocate(Bpp(nBas,2),Z(nBas),eGF2(nBas),eOld(nBas),error_diis(nBas,max_diis),e_diis(nBas,max_diis))
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! Initialization
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Conv = 1d0
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nSCF = 0
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n_diis = 0
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e_diis(:,:) = 0d0
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error_diis(:,:) = 0d0
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eGF2(:) = e0(:)
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eOld(:) = e0(:)
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!------------------------------------------------------------------------
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! Main SCF loop
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!------------------------------------------------------------------------
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do while(Conv > thresh .and. nSCF < maxSCF)
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! Frequency-dependent second-order contribution
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Bpp(:,:) = 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 = eGF2(p) + e0(a) - e0(i) - e0(j)
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Bpp(p,1) = Bpp(p,1) &
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+ (2d0*V(p,a,i,j) - V(p,a,j,i))*V(p,a,i,j)/eps
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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 = eGF2(p) + e0(i) - e0(a) - e0(b)
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Bpp(p,2) = Bpp(p,2) &
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+ (2d0*V(p,i,a,b) - V(p,i,b,a))*V(p,i,a,b)/eps
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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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! Compute the renormalization factor
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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 = eGF2(p) + e0(a) - e0(i) - e0(j)
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Z(p) = Z(p) - (2d0*V(p,a,i,j) - V(p,a,j,i))*V(p,a,i,j)/eps**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 = eGF2(p) + e0(i) - e0(a) - e0(b)
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Z(p) = Z(p) - (2d0*V(p,i,a,b) - V(p,i,b,a))*V(p,i,a,b)/eps**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(:) = e0(:) + Z(:)*(Bpp(:,1) + Bpp(:,2))
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else
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eGF2(:) = e0(:) + Bpp(:,1) + Bpp(:,2)
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end if
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Conv = maxval(abs(eGF2 - eOld))
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! Print results
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call print_GF2(nBas,nO,nSCF,Conv,e0,eGF2)
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! DIIS extrapolation
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n_diis = min(n_diis+1,max_diis)
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call DIIS_extrapolation(rcond,nBas,nBas,n_diis,error_diis,e_diis,eGF2-eOld,eGF2)
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if(abs(rcond) < 1d-15) n_diis = 0
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eOld(:) = eGF2(:)
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! Increment
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nSCF = nSCF + 1
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end do
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!------------------------------------------------------------------------
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! End main SCF loop
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!------------------------------------------------------------------------
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! Did it actually converge?
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if(nSCF == maxSCF+1) then
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write(*,*)
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write(*,*)'!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!'
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write(*,*)' Convergence failed '
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write(*,*)'!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!'
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write(*,*)
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end if
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end subroutine GF2_diag
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