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https://github.com/pfloos/quack
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29 lines
753 B
Fortran
29 lines
753 B
Fortran
recursive function HRROv(AngMomA,AngMomB,ExpPi,CenterAB,CenterPA) &
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result(Gab)
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! Horizontal recurrence relations for one-electron overlap integrals
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implicit none
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! Input variables
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integer,intent(in) :: AngMomA,AngMomB
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double precision,intent(in) :: ExpPi
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double precision,intent(in) :: CenterAB,CenterPA
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! Local variables
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double precision :: VRROv
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double precision :: Gab
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if(AngMomB < 0) then
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Gab = 0d0
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else
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if(AngMomB == 0) then
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Gab = VRROv(AngMomA,ExpPi,CenterPA)
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else
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Gab = HRROv(AngMomA+1,AngMomB-1,ExpPi,CenterAB,CenterPA) &
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+ CenterAB*HRROv(AngMomA,AngMomB-1,ExpPi,CenterAB,CenterPA)
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end if
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end if
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end function HRROv
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