mirror of https://github.com/pfloos/quack
94 lines
2.7 KiB
Fortran
94 lines
2.7 KiB
Fortran
subroutine ppLR(TDA,nOO,nVV,Bpp,Cpp,Dpp,Om1,X1,Y1,Om2,X2,Y2,EcRPA)
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! Solve the pp-RPA linear eigenvalue problem
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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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integer,intent(in) :: nOO
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integer,intent(in) :: nVV
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double precision,intent(in) :: Bpp(nVV,nOO)
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double precision,intent(in) :: Cpp(nVV,nVV)
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double precision,intent(in) :: Dpp(nOO,nOO)
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! Local variables
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double precision :: trace_matrix
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double precision :: EcRPA1
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double precision :: EcRPA2
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double precision,allocatable :: M(:,:)
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double precision,allocatable :: Z(:,:)
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double precision,allocatable :: Om(:)
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! Output variables
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double precision,intent(out) :: Om1(nVV)
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double precision,intent(out) :: X1(nVV,nVV)
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double precision,intent(out) :: Y1(nOO,nVV)
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double precision,intent(out) :: Om2(nOO)
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double precision,intent(out) :: X2(nVV,nOO)
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double precision,intent(out) :: Y2(nOO,nOO)
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double precision,intent(out) :: EcRPA
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! Memory allocation
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allocate(M(nOO+nVV,nOO+nVV),Z(nOO+nVV,nOO+nVV),Om(nOO+nVV))
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!-------------------------------------------------!
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! Solve the p-p eigenproblem !
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!-------------------------------------------------!
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! !
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! | C B | | X1 X2 | | w1 0 | | X1 X2 | !
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! | | | | = | | | | !
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! | -Bt -D | | Y1 Y2 | | 0 w2 | | Y1 Y2 | !
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! !
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!-------------------------------------------------!
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if(TDA) then
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X1(:,:) = +Cpp(:,:)
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Y1(:,:) = 0d0
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if(nVV > 0) call diagonalize_matrix(nVV,X1,Om1)
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X2(:,:) = 0d0
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Y2(:,:) = -Dpp(:,:)
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if(nOO > 0) call diagonalize_matrix(nOO,Y2,Om2)
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else
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! Diagonal blocks
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M( 1:nVV , 1:nVV) = + Cpp(1:nVV,1:nVV)
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M(nVV+1:nVV+nOO,nVV+1:nVV+nOO) = - Dpp(1:nOO,1:nOO)
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! Off-diagonal blocks
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M( 1:nVV ,nVV+1:nOO+nVV) = - Bpp(1:nVV,1:nOO)
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M(nVV+1:nOO+nVV, 1:nVV) = + transpose(Bpp(1:nVV,1:nOO))
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! call matout(nOO,nOO,Dpp)
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! Diagonalize the p-p matrix
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if(nOO+nVV > 0) call diagonalize_general_matrix(nOO+nVV,M,Om,Z)
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! Split the various quantities in p-p and h-h parts
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call sort_ppRPA(nOO,nVV,Om,Z,Om1,X1,Y1,Om2,X2,Y2)
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end if
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! Compute the RPA correlation energy
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EcRPA = 0.5d0*( sum(Om1) - sum(Om2) - trace_matrix(nVV,Cpp) - trace_matrix(nOO,Dpp) )
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EcRPA1 = +sum(Om1) - trace_matrix(nVV,Cpp)
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EcRPA2 = -sum(Om2) - trace_matrix(nOO,Dpp)
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if(abs(EcRPA - EcRPA1) > 1d-6 .or. abs(EcRPA - EcRPA2) > 1d-6) &
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print*,'!!! Issue in pp-RPA linear reponse calculation RPA1 != RPA2 !!!'
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end subroutine
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