mirror of https://github.com/pfloos/quack
37 lines
1.3 KiB
Fortran
37 lines
1.3 KiB
Fortran
recursive function VRRF12(AngMomA,AngMomC,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
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result(Gac)
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! Compute two-electron integrals over Gaussian geminals
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implicit none
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! Input variables
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integer,intent(in) :: AngMomA,AngMomC
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double precision,intent(in) :: ExpPGQi
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double precision,intent(in) :: fG,gP,gG,gQ
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double precision,intent(in) :: CenterPQSq,CenterRA,CenterRC
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! Output variables
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double precision :: Gac
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if(AngMomA < 0 .or. AngMomC < 0) then
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Gac = 0d0
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else
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if(AngMomA == 0 .and. AngMomC == 0) then
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Gac = sqrt(fG)*exp(-CenterPQSq/ExpPGQi)
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else
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If(AngMomC == 0) then
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Gac = CenterRA*VRRF12(AngMomA-1,AngMomC,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
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+ dble(AngMomA-1)*gP*VRRF12(AngMomA-2,AngMomC,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC)
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else
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Gac = CenterRC*VRRF12(AngMomA,AngMomC-1,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
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+ dble(AngMomA)*gG*VRRF12(AngMomA-1,AngMomC-1,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC) &
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+ dble(AngMomC-1)*gQ*VRRF12(AngMomA,AngMomC-2,fG,gP,gG,gQ,ExpPGQi,CenterPQSq,CenterRA,CenterRC)
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endIf
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endIf
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endIf
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end function VRRF12
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