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quack/src/IntPak/VRRF12.f90

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Fortran
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2019-02-07 22:49:12 +01:00
recursive function VRRF12(AngMomA,AngMomC,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
result(Gac)
! Compute two-electron integrals over Gaussian geminals
implicit none
! Input variables
integer,intent(in) :: AngMomA,AngMomC
double precision,intent(in) :: ExpPGQi
double precision,intent(in) :: fG,gP,gG,gQ
double precision,intent(in) :: CenterPQSq,CenterRA,CenterRC
! Output variables
double precision :: Gac
if(AngMomA < 0 .or. AngMomC < 0) then
Gac = 0d0
else
if(AngMomA == 0 .and. AngMomC == 0) then
Gac = sqrt(fG)*exp(-CenterPQSq/ExpPGQi)
else
If(AngMomC == 0) then
Gac = CenterRA*VRRF12(AngMomA-1,AngMomC,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
+ dble(AngMomA-1)*gP*VRRF12(AngMomA-2,AngMomC,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC)
else
Gac = CenterRC*VRRF12(AngMomA,AngMomC-1,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
+ dble(AngMomA)*gG*VRRF12(AngMomA-1,AngMomC-1,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
+ dble(AngMomC-1)*gQ*VRRF12(AngMomA,AngMomC-2,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC)
endIf
endIf
endIf
end function VRRF12