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quack/src/GW/Bethe_Salpeter.f90

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)
! Compute the Bethe-Salpeter excitation energies
implicit none
include 'parameters.h'
! Input variables
logical,intent(in) :: TDA_W
logical,intent(in) :: TDA
logical,intent(in) :: dBSE
logical,intent(in) :: dTDA
logical,intent(in) :: evDyn
logical,intent(in) :: singlet
logical,intent(in) :: triplet
double precision,intent(in) :: eta
integer,intent(in) :: nBas
integer,intent(in) :: nC
integer,intent(in) :: nO
integer,intent(in) :: nV
integer,intent(in) :: nR
integer,intent(in) :: nS
double precision,intent(in) :: eW(nBas)
double precision,intent(in) :: eGW(nBas)
double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas)
double precision,intent(in) :: dipole_int(nBas,nBas,ncart)
! Local variables
integer :: ispin
integer :: isp_W
double precision :: EcRPA
double precision,allocatable :: OmRPA(:)
double precision,allocatable :: XpY_RPA(:,:)
double precision,allocatable :: XmY_RPA(:,:)
double precision,allocatable :: rho_RPA(:,:,:)
double precision,allocatable :: OmBSE(:,:)
double precision,allocatable :: XpY_BSE(:,:,:)
double precision,allocatable :: XmY_BSE(:,:,:)
! Output variables
double precision,intent(out) :: EcBSE(nspin)
! Memory allocation
allocate(OmRPA(nS),XpY_RPA(nS,nS),XmY_RPA(nS,nS),rho_RPA(nBas,nBas,nS))
allocate(OmBSE(nS,nspin),XpY_BSE(nS,nS,nspin),XmY_BSE(nS,nS,nspin))
!---------------------------------
! Compute (singlet) RPA screening
!---------------------------------
isp_W = 1
EcRPA = 0d0
call linear_response(isp_W,.true.,TDA_W,.false.,eta,nBas,nC,nO,nV,nR,nS,1d0,eW,ERI,OmRPA, &
rho_RPA,EcRPA,OmRPA,XpY_RPA,XmY_RPA)
call excitation_density(nBas,nC,nO,nR,nS,ERI,XpY_RPA,rho_RPA)
!-------------------
! Singlet manifold
!-------------------
if(singlet) then
ispin = 1
EcBSE(ispin) = 0d0
! Compute BSE excitation energies
call linear_response(ispin,.true.,TDA,.true.,eta,nBas,nC,nO,nV,nR,nS,1d0,eGW,ERI,OmRPA, &
rho_RPA,EcBSE(ispin),OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
call print_excitation('BSE@GW ',ispin,nS,OmBSE(:,ispin))
call print_transition_vectors(.true.,nBas,nC,nO,nV,nR,nS,dipole_int, &
OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
!-------------------------------------------------
! Compute the dynamical screening at the BSE level
!-------------------------------------------------
if(dBSE) then
! Compute dynamic correction for BSE via perturbation theory (iterative or renormalized)
if(evDyn) then
call Bethe_Salpeter_dynamic_perturbation_iterative(dTDA,eta,nBas,nC,nO,nV,nR,nS,eGW,dipole_int,OmRPA,rho_RPA, &
OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
else
call Bethe_Salpeter_dynamic_perturbation(dTDA,eta,nBas,nC,nO,nV,nR,nS,eW,eGW,dipole_int,OmRPA,rho_RPA, &
OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
end if
end if
end if
!-------------------
! Triplet manifold
!-------------------
if(triplet) then
ispin = 2
EcBSE(ispin) = 0d0
! Compute BSE excitation energies
call linear_response(ispin,.true.,TDA,.true.,eta,nBas,nC,nO,nV,nR,nS,1d0,eGW,ERI,OmRPA, &
rho_RPA,EcBSE(ispin),OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
call print_excitation('BSE@GW ',ispin,nS,OmBSE(:,ispin))
call print_transition_vectors(.false.,nBas,nC,nO,nV,nR,nS,dipole_int, &
OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
!-------------------------------------------------
! Compute the dynamical screening at the BSE level
!-------------------------------------------------
if(dBSE) then
! Compute dynamic correction for BSE via perturbation theory (iterative or renormalized)
if(evDyn) then
call Bethe_Salpeter_dynamic_perturbation_iterative(dTDA,eta,nBas,nC,nO,nV,nR,nS,eGW,dipole_int,OmRPA,rho_RPA, &
OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
else
call Bethe_Salpeter_dynamic_perturbation(dTDA,eta,nBas,nC,nO,nV,nR,nS,eW,eGW,dipole_int,OmRPA,rho_RPA, &
OmBSE(:,ispin),XpY_BSE(:,:,ispin),XmY_BSE(:,:,ispin))
end if
end if
end if
end subroutine Bethe_Salpeter