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https://github.com/pfloos/quack
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144 lines
4.8 KiB
Fortran
144 lines
4.8 KiB
Fortran
subroutine Bethe_Salpeter(TDA_W,TDA,dBSE,dTDA,evDyn,singlet,triplet,eta,nBas,nC,nO,nV,nR,nS,ERI,dipole_int,eW,eGW,EcBSE)
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! Compute the Bethe-Salpeter excitation energies
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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_W
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logical,intent(in) :: TDA
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logical,intent(in) :: dBSE
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logical,intent(in) :: dTDA
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logical,intent(in) :: evDyn
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logical,intent(in) :: singlet
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logical,intent(in) :: triplet
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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) :: eW(nBas)
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double precision,intent(in) :: eGW(nBas)
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double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas)
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double precision,intent(in) :: dipole_int(nBas,nBas,ncart)
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! Local variables
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integer :: ispin
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integer :: isp_W
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double precision :: EcRPA
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double precision,allocatable :: OmRPA(:)
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double precision,allocatable :: XpY_RPA(:,:)
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double precision,allocatable :: XmY_RPA(:,:)
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double precision,allocatable :: rho_RPA(:,:,:)
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double precision,allocatable :: OmBSE(:,:)
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double precision,allocatable :: XpY_BSE(:,:,:)
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double precision,allocatable :: XmY_BSE(:,:,:)
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! Output variables
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double precision,intent(out) :: EcBSE(nspin)
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! Memory allocation
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allocate(OmRPA(nS),XpY_RPA(nS,nS),XmY_RPA(nS,nS),rho_RPA(nBas,nBas,nS))
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allocate(OmBSE(nS,nspin),XpY_BSE(nS,nS,nspin),XmY_BSE(nS,nS,nspin))
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!---------------------------------
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! Compute (singlet) RPA screening
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!---------------------------------
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isp_W = 1
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EcRPA = 0d0
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call linear_response(isp_W,.true.,TDA_W,.false.,eta,nBas,nC,nO,nV,nR,nS,1d0,eW,ERI,OmRPA, &
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rho_RPA,EcRPA,OmRPA,XpY_RPA,XmY_RPA)
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call excitation_density(nBas,nC,nO,nR,nS,ERI,XpY_RPA,rho_RPA)
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!-------------------
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! Singlet manifold
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!-------------------
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if(singlet) then
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ispin = 1
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EcBSE(ispin) = 0d0
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! Compute BSE excitation energies
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call linear_response(ispin,.true.,TDA,.true.,eta,nBas,nC,nO,nV,nR,nS,1d0,eGW,ERI,OmRPA, &
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rho_RPA,EcBSE(ispin),OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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call print_excitation('BSE@GW ',ispin,nS,OmBSE(:,ispin))
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call print_transition_vectors(.true.,nBas,nC,nO,nV,nR,nS,dipole_int, &
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OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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!-------------------------------------------------
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! Compute the dynamical screening at the BSE level
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!-------------------------------------------------
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if(dBSE) then
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! Compute dynamic correction for BSE via perturbation theory (iterative or renormalized)
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if(evDyn) then
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call Bethe_Salpeter_dynamic_perturbation_iterative(dTDA,eta,nBas,nC,nO,nV,nR,nS,eGW,dipole_int,OmRPA,rho_RPA, &
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OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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else
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call Bethe_Salpeter_dynamic_perturbation(dTDA,eta,nBas,nC,nO,nV,nR,nS,eW,eGW,dipole_int,OmRPA,rho_RPA, &
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OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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end if
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end if
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end if
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!-------------------
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! Triplet manifold
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!-------------------
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if(triplet) then
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ispin = 2
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EcBSE(ispin) = 0d0
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! Compute BSE excitation energies
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call linear_response(ispin,.true.,TDA,.true.,eta,nBas,nC,nO,nV,nR,nS,1d0,eGW,ERI,OmRPA, &
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rho_RPA,EcBSE(ispin),OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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call print_excitation('BSE@GW ',ispin,nS,OmBSE(:,ispin))
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call print_transition_vectors(.false.,nBas,nC,nO,nV,nR,nS,dipole_int, &
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OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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!-------------------------------------------------
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! Compute the dynamical screening at the BSE level
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!-------------------------------------------------
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if(dBSE) then
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! Compute dynamic correction for BSE via perturbation theory (iterative or renormalized)
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if(evDyn) then
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call Bethe_Salpeter_dynamic_perturbation_iterative(dTDA,eta,nBas,nC,nO,nV,nR,nS,eGW,dipole_int,OmRPA,rho_RPA, &
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OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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else
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call Bethe_Salpeter_dynamic_perturbation(dTDA,eta,nBas,nC,nO,nV,nR,nS,eW,eGW,dipole_int,OmRPA,rho_RPA, &
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OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
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end if
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end if
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end if
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end subroutine Bethe_Salpeter
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