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119 lines
3.4 KiB
Fortran
119 lines
3.4 KiB
Fortran
subroutine Bethe_Salpeter_AB_matrix_dynamic(eta,nBas,nC,nO,nV,nR,nS,lambda,eGW,OmRPA,rhO_RPA,OmBSE,Ap,Am,Bp,Bm)
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! Compute the dynamic part of the Bethe-Salpeter equation matrices
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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) :: nBas,nC,nO,nV,nR,nS
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double precision,intent(in) :: eta
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double precision,intent(in) :: lambda
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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) :: rho_RPA(nBas,nBas,nS)
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double precision,intent(in) :: OmBSE
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! Local variables
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integer :: maxS
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double precision :: chi_A,chi_B
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double precision :: chi_Ap,chi_Bp,eps_Ap,eps_Bp
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double precision :: chi_Am,chi_Bm,eps_Am,eps_Bm
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integer :: i,j,a,b,ia,jb,kc
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! Output variables
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double precision,intent(out) :: Ap(nS,nS)
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double precision,intent(out) :: Am(nS,nS)
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double precision,intent(out) :: Bp(nS,nS)
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double precision,intent(out) :: Bm(nS,nS)
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! Initialization
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Ap(:,:) = 0d0
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Am(:,:) = 0d0
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Bp(:,:) = 0d0
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Bm(:,:) = 0d0
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! Number of poles taken into account
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maxS = nS
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! Build dynamic A matrix
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ia = 0
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do i=nC+1,nO
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do a=nO+1,nBas-nR
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ia = ia + 1
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jb = 0
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do j=nC+1,nO
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do b=nO+1,nBas-nR
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jb = jb + 1
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chi_A = 0d0
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chi_B = 0d0
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do kc=1,maxS
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chi_A = chi_A + rho_RPA(i,j,kc)*rho_RPA(a,b,kc)*OmRPA(kc)/(OmRPA(kc)**2 + eta**2)
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chi_B = chi_B + rho_RPA(i,b,kc)*rho_RPA(a,j,kc)*OmRPA(kc)/(OmRPA(kc)**2 + eta**2)
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enddo
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Ap(ia,jb) = Ap(ia,jb) - 4d0*lambda*chi_A
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Am(ia,jb) = Am(ia,jb) - 4d0*lambda*chi_A
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Bp(ia,jb) = Bp(ia,jb) - 4d0*lambda*chi_B
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Bm(ia,jb) = Bm(ia,jb) - 4d0*lambda*chi_B
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chi_Ap = 0d0
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chi_Am = 0d0
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chi_Bp = 0d0
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chi_Bm = 0d0
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do kc=1,maxS
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eps_Ap = + OmBSE - OmRPA(kc) - (eGW(a) - eGW(j))
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chi_Ap = chi_Ap + rho_RPA(i,j,kc)*rho_RPA(a,b,kc)*eps_Ap/(eps_Ap**2 + eta**2)
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eps_Ap = + OmBSE - OmRPA(kc) - (eGW(b) - eGW(i))
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chi_Ap = chi_Ap + rho_RPA(i,j,kc)*rho_RPA(a,b,kc)*eps_Ap/(eps_Ap**2 + eta**2)
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eps_Am = - OmBSE - OmRPA(kc) - (eGW(a) - eGW(j))
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chi_Am = chi_Am + rho_RPA(i,j,kc)*rho_RPA(a,b,kc)*eps_Am/(eps_Am**2 + eta**2)
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eps_Am = - OmBSE - OmRPA(kc) - (eGW(b) - eGW(i))
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chi_Am = chi_Am + rho_RPA(i,j,kc)*rho_RPA(a,b,kc)*eps_Am/(eps_Am**2 + eta**2)
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eps_Bp = - OmRPA(kc) - (eGW(a) - eGW(b))
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chi_Bp = chi_Bp + rho_RPA(i,b,kc)*rho_RPA(a,j,kc)*eps_Bp/(eps_Bp**2 + eta**2)
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eps_Bp = - OmRPA(kc) - (eGW(j) - eGW(i))
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chi_Bp = chi_Bp + rho_RPA(i,b,kc)*rho_RPA(a,j,kc)*eps_Bp/(eps_Bp**2 + eta**2)
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eps_Bm = - OmRPA(kc) - (eGW(a) - eGW(b))
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chi_Bm = chi_Bm + rho_RPA(i,b,kc)*rho_RPA(a,j,kc)*eps_Bm/(eps_Bm**2 + eta**2)
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eps_Bm = - OmRPA(kc) - (eGW(j) - eGW(i))
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chi_Bm = chi_Bm + rho_RPA(i,b,kc)*rho_RPA(a,j,kc)*eps_Bm/(eps_Bm**2 + eta**2)
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enddo
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Ap(ia,jb) = Ap(ia,jb) - 2d0*lambda*chi_Ap
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Am(ia,jb) = Am(ia,jb) - 2d0*lambda*chi_Am
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Bp(ia,jb) = Bp(ia,jb) - 2d0*lambda*chi_Bp
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Bm(ia,jb) = Bm(ia,jb) - 2d0*lambda*chi_Bm
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enddo
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enddo
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enddo
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enddo
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end subroutine Bethe_Salpeter_AB_matrix_dynamic
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