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https://github.com/pfloos/quack
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134 lines
4.5 KiB
Fortran
134 lines
4.5 KiB
Fortran
subroutine Bethe_Salpeter_dynamic_perturbation_iterative(TDA,eta,nBas,nC,nO,nV,nR,nS,eGW,OmRPA,OmBSE,XpY,XmY,rho)
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! Compute self-consistently the dynamical effects via perturbation theory for BSE
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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) :: TDA
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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) :: eGW(nBas)
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double precision,intent(in) :: OmRPA(nS)
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double precision,intent(in) :: OmBSE(nS)
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double precision,intent(in) :: XpY(nS,nS)
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double precision,intent(in) :: XmY(nS,nS)
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double precision,intent(in) :: rho(nBas,nBas,nS)
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! Local variables
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logical :: TDA_dyn = .true.
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integer :: ia
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integer,parameter :: maxS = 10
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double precision :: gapGW
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integer :: nSCF
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integer :: maxSCF = 10
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double precision :: Conv
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double precision :: thresh = 1d-5
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double precision,allocatable :: OmDyn(:)
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double precision,allocatable :: OmOld(:)
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double precision,allocatable :: X(:)
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double precision,allocatable :: Y(:)
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double precision,allocatable :: A_dyn(:,:)
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double precision,allocatable :: B_dyn(:,:)
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double precision,allocatable :: ZA_dyn(:,:)
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double precision,allocatable :: ZB_dyn(:,:)
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! Memory allocation
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allocate(OmDyn(nS),OmOld(nS),X(nS),Y(nS),A_dyn(nS,nS))
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if(.not.TDA_dyn) allocate(B_dyn(nS,nS))
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gapGW = eGW(nO+1) - eGW(nO)
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Conv = 1d0
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nSCF = 0
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OmOld(:) = OmBSE(:)
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write(*,*) '---------------------------------------------------------------------------------------------------'
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write(*,*) ' First-order dynamical correction to static Bethe-Salpeter excitation energies '
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write(*,*) '---------------------------------------------------------------------------------------------------'
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write(*,*)
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do while(Conv > thresh .and. nSCF < maxSCF)
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nSCF = nSCF + 1
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write(*,*) '---------------------------------------------------------------------------------------------------'
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write(*,'(2X,A15,I3)') 'Iteration n.',nSCF
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write(*,*) '---------------------------------------------------------------------------------------------------'
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write(*,'(2X,A5,1X,A20,1X,A20,1X,A20)') '#','Static (eV)','Dynamic (eV)','Correction (eV)'
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write(*,*) '---------------------------------------------------------------------------------------------------'
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do ia=1,min(nS,maxS)
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X(:) = 0.5d0*(XpY(ia,:) + XmY(ia,:))
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Y(:) = 0.5d0*(XpY(ia,:) - XmY(ia,:))
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! Resonant part of the BSE correction
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call Bethe_Salpeter_A_matrix_dynamic(eta,nBas,nC,nO,nV,nR,nS,1d0,eGW(:),OmRPA(:),OmOld(ia),rho(:,:,:),A_dyn(:,:))
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! First-order correction
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if(TDA_dyn) then
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OmDyn(ia) = dot_product(X(:),matmul(A_dyn(:,:),X(:)))
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else
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! Anti-resonant part of the BSE correction
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call Bethe_Salpeter_B_matrix_dynamic(eta,nBas,nC,nO,nV,nR,nS,1d0,eGW(:),OmRPA(:),OmOld(ia),rho(:,:,:),B_dyn(:,:))
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OmDyn(ia) = dot_product(X(:),matmul(A_dyn(:,:),X(:))) &
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- dot_product(Y(:),matmul(A_dyn(:,:),Y(:))) &
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+ dot_product(X(:),matmul(B_dyn(:,:),Y(:))) &
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- dot_product(Y(:),matmul(B_dyn(:,:),X(:)))
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end if
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write(*,'(2X,I5,5X,F15.6,5X,F15.6,5X,F15.6)') &
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ia,OmBSE(ia)*HaToeV,(OmBSE(ia)+OmDyn(ia))*HaToeV,OmDyn(ia)*HaToeV
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if(OmBSE(ia) > gapGW) write(*,*) ' !!! BSE neutral excitation larger than the GW gap !!! '
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end do
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Conv = maxval(abs(OmBSE(:) + OmDyn(:) - OmOld(:)))
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OmOld(:) = OmBSE(:) + OmDyn(:)
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write(*,*) '---------------------------------------------------------------------------------------------------'
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write(*,'(2X,A20,1X,F10.6)') ' Convergence = ',Conv
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write(*,*) '---------------------------------------------------------------------------------------------------'
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write(*,*)
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end do
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! Did it actually converge?
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if(nSCF == maxSCF) 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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endif
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end subroutine Bethe_Salpeter_dynamic_perturbation_iterative
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