mirror of
https://gitlab.com/scemama/qp_plugins_scemama.git
synced 2024-12-23 04:43:38 +01:00
72 lines
1.8 KiB
Fortran
72 lines
1.8 KiB
Fortran
subroutine MP2(nBas,nC,nR,ERI,ENuc,EHF,e,EcMP2)
|
|
|
|
! Perform third-order Moller-Plesset calculation
|
|
|
|
implicit none
|
|
|
|
! Input variables
|
|
|
|
integer,intent(in) :: nBas,nC,nR
|
|
double precision,intent(in) :: ENuc,EHF
|
|
double precision,intent(in) :: ERI(nBas,nBas,nBas,nBas),e(nBas)
|
|
|
|
! Local variables
|
|
|
|
integer :: i,j,a,b
|
|
double precision :: eps,E2a,E2b
|
|
|
|
! Output variables
|
|
|
|
double precision,intent(out) :: EcMP2(3)
|
|
|
|
! Hello world
|
|
|
|
write(*,*)
|
|
write(*,*)'************************************************'
|
|
write(*,*)'| Moller-Plesset second-order calculation |'
|
|
write(*,*)'************************************************'
|
|
write(*,*)
|
|
|
|
! Compute MP2 energy
|
|
|
|
E2a = 0d0
|
|
E2b = 0d0
|
|
do i=nC+1,spin_occ_num
|
|
do j=nC+1,spin_occ_num
|
|
do a=spin_occ_num+1,nBas-nR
|
|
do b=spin_occ_num+1,nBas-nR
|
|
|
|
eps = e(i) + e(j) - e(a) - e(b)
|
|
|
|
! Second-order ring diagram
|
|
|
|
E2a = E2a + ERI(i,j,a,b)*ERI(i,j,a,b)/eps
|
|
|
|
! Second-order exchange diagram
|
|
|
|
E2b = E2b + ERI(i,j,a,b)*ERI(i,j,b,a)/eps
|
|
|
|
enddo
|
|
enddo
|
|
enddo
|
|
enddo
|
|
|
|
EcMP2(2) = 2d0*E2a
|
|
EcMP2(3) = -E2b
|
|
EcMP2(1) = EcMP2(2) + EcMP2(3)
|
|
|
|
write(*,*)
|
|
write(*,'(A32)') '-----------------------'
|
|
write(*,'(A32)') ' MP2 calculation '
|
|
write(*,'(A32)') '-----------------------'
|
|
write(*,'(A32,1X,F16.10)') ' MP2 correlation energy',EcMP2(1)
|
|
write(*,'(A32,1X,F16.10)') ' Direct part ',EcMP2(2)
|
|
write(*,'(A32,1X,F16.10)') ' Exchange part ',EcMP2(3)
|
|
write(*,'(A32)') '-----------------------'
|
|
write(*,'(A32,1X,F16.10)') ' MP2 electronic energy',EHF + EcMP2(1)
|
|
write(*,'(A32,1X,F16.10)') ' MP2 total energy',ENuc + EHF + EcMP2(1)
|
|
write(*,'(A32)') '-----------------------'
|
|
write(*,*)
|
|
|
|
end subroutine MP2
|