mirror of https://github.com/pfloos/quack
75 lines
1.9 KiB
Fortran
75 lines
1.9 KiB
Fortran
subroutine OvInt(npOv,nSigpOv,ExpA,CenterA,AngMomA,ExpB,CenterB,AngMomB,pOv)
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! Compute one-electron overlap integrals
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implicit none
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! Input variables
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double precision,intent(in) :: ExpA,ExpB
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double precision,intent(in) :: CenterA(3),CenterB(3)
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integer,intent(in) :: AngMomA(3),AngMomB(3)
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! Local variables
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double precision :: ExpAi,ExpBi
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double precision :: ExpP,ExpPi
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double precision :: CenterP(3),CenterAB(3),CenterPA(3)
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double precision :: NormABSq
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double precision :: G
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double precision :: HRROv
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integer :: i
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double precision :: pi
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double precision :: start_RR,finish_RR,t_RR
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double precision :: Gab(3)
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! Output variables
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integer,intent(inout) :: npOv,nSigpOv
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double precision,intent(out) :: pOv
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pi = 4d0*atan(1d0)
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! Pre-computed shell quantities
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ExpAi = 1d0/ExpA
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ExpBi = 1d0/ExpB
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! Pre-computed quantities for shell-pair AB
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ExpP = ExpA + ExpB
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ExpPi = 1d0/ExpP
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NormABSq = 0d0
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Do i=1,3
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CenterP(i) = (ExpA*CenterA(i) + ExpB*CenterB(i))*ExpPi
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CenterPA(i) = CenterP(i) - CenterA(i)
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CenterAB(i) = CenterA(i) - CenterB(i)
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NormABSq = NormABSq + CenterAB(i)**2
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Enddo
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G = (pi*ExpPi)**(1.5d0)*exp(-NormABSq/(ExpAi+ExpBi))
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!------------------------------------------------------------------------
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! Launch reccurence relations!
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!------------------------------------------------------------------------
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call cpu_time(start_RR)
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! Loop over cartesian directions
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Do i=1,3
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Gab(i) = HRROv(AngMomA(i),AngMomB(i),ExpPi,CenterAB(i),CenterPA(i))
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Enddo
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call cpu_time(finish_RR)
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pOv = G*Gab(1)*Gab(2)*Gab(3)
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t_RR = finish_RR - start_RR
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! Print result
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npOv = npOv + 1
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if(abs(pOv) > 1d-15) then
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nSigpOv = nSigpOv + 1
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endif
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end subroutine OvInt
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