mirror of
https://github.com/pfloos/quack
synced 2024-06-26 15:12:17 +02:00
93 lines
2.1 KiB
Fortran
93 lines
2.1 KiB
Fortran
subroutine Ec_AC(ispin,dRPA,nBas,nC,nO,nV,nR,nS,ERI,XpY,XmY,EcAC)
|
|
|
|
! Compute the correlation energy via the adiabatic connection formula
|
|
|
|
implicit none
|
|
include 'parameters.h'
|
|
|
|
! Input variables
|
|
|
|
integer,intent(in) :: ispin
|
|
logical,intent(in) :: dRPA
|
|
integer,intent(in) :: nBas,nC,nO,nV,nR,nS
|
|
double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas)
|
|
double precision,intent(in) :: XpY(nS,nS)
|
|
double precision,intent(in) :: XmY(nS,nS)
|
|
|
|
! Local variables
|
|
|
|
integer :: i,j,a,b
|
|
integer :: ia,jb,kc
|
|
double precision :: delta_spin
|
|
double precision :: delta_dRPA
|
|
double precision,allocatable :: P(:,:)
|
|
double precision,allocatable :: Ap(:,:)
|
|
double precision,allocatable :: Bp(:,:)
|
|
double precision,allocatable :: X(:,:)
|
|
double precision,allocatable :: Y(:,:)
|
|
double precision,external :: trace_matrix
|
|
|
|
! Output variables
|
|
|
|
double precision,intent(out) :: EcAC
|
|
|
|
! Singlet or triplet manifold?
|
|
|
|
delta_spin = 0d0
|
|
if(ispin == 1) delta_spin = +1d0
|
|
if(ispin == 2) delta_spin = -1d0
|
|
|
|
! Direct RPA
|
|
|
|
delta_dRPA = 0d0
|
|
if(dRPA) delta_dRPA = 1d0
|
|
|
|
! Memory allocation
|
|
|
|
allocate(P(nS,nS),Ap(nS,nS),Bp(nS,nS),X(nS,nS),Y(nS,nS))
|
|
|
|
! Compute P = (X+Y)(X+Y) - 1
|
|
|
|
P(:,:) = matmul(transpose(XpY),XpY)
|
|
|
|
do ia=1,nS
|
|
P(ia,ia) = P(ia,ia) - 1d0
|
|
enddo
|
|
|
|
! Compute Aiajb = (ia|bj) and Biajb = (ia|jb)
|
|
|
|
ia = 0
|
|
do i=nC+1,nO
|
|
do a=nO+1,nBas-nR
|
|
ia = ia + 1
|
|
jb = 0
|
|
do j=nC+1,nO
|
|
do b=nO+1,nBas-nR
|
|
jb = jb + 1
|
|
|
|
Ap(ia,jb) = (1d0 + delta_spin)*ERI(i,b,a,j)
|
|
Bp(ia,jb) = (1d0 + delta_spin)*ERI(i,j,b,a)
|
|
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
|
|
! Compute Tr(A x P)
|
|
|
|
! EcAC = trace_matrix(nS,matmul(Ap,P))
|
|
|
|
! print*,'EcAC =',EcAC
|
|
|
|
X(:,:) = 0.5d0*(XpY(:,:) + XmY(:,:))
|
|
Y(:,:) = 0.5d0*(XpY(:,:) - XmY(:,:))
|
|
|
|
EcAC = trace_matrix(nS,matmul(X,matmul(Bp,transpose(Y))) + matmul(Y,matmul(Bp,transpose(X)))) &
|
|
+ trace_matrix(nS,matmul(X,matmul(Ap,transpose(X))) + matmul(Y,matmul(Ap,transpose(Y)))) &
|
|
- trace_matrix(nS,Ap)
|
|
|
|
! print*,'EcAC =',EcAC
|
|
|
|
end subroutine Ec_AC
|
|
|