mirror of https://github.com/pfloos/quack
131 lines
4.8 KiB
Fortran
131 lines
4.8 KiB
Fortran
recursive function VRR2e(m,AngMomBra,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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result(a1a2)
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! Compute two-electron integrals over Gaussian geminals
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implicit none
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include 'parameters.h'
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! Input variables
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integer,intent(in) :: m
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integer,intent(in) :: AngMomBra(2,3)
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integer,intent(in) :: maxm
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double precision,intent(in) :: Om(0:maxm),ExpZi(2),ExpY(2,2)
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double precision,intent(in) :: CenterZA(2,3),CenterY(2,2,3)
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! Local variables
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logical :: NegAngMomBra(2)
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integer :: TotAngMomBra(2)
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integer :: a1m(2,3),a2m(2,3)
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integer :: a1mm(2,3),a2mm(2,3)
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integer :: a1m2m(2,3)
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double precision :: fZ(2)
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integer :: i,j,xyz
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! Output variables
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double precision :: a1a2
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do i=1,2
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NegAngMomBra(i) = AngMomBra(i,1) < 0 .or. AngMomBra(i,2) < 0 .or. AngMomBra(i,3) < 0
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TotAngMomBra(i) = AngMomBra(i,1) + AngMomBra(i,2) + AngMomBra(i,3)
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enddo
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fZ(1) = ExpY(1,2)*ExpZi(1)
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fZ(2) = ExpY(1,2)*ExpZi(2)
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!------------------------------------------------------------------------
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! Termination condition
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!------------------------------------------------------------------------
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! if(NegAngMomBra(1) .or. NegAngMomBra(2)) then
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! a1a2 = 0d0
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!------------------------------------------------------------------------
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! Fundamental integral: (00|00)^m
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!------------------------------------------------------------------------
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! elseif(TotAngMomBra(1) == 0 .and. TotAngMomBra(2) == 0) then
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if(TotAngMomBra(1) == 0 .and. TotAngMomBra(2) == 0) then
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a1a2 = Om(m)
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!------------------------------------------------------------------------
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! 1st vertical recurrence relation (4 terms): (a+0|00)^m
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!------------------------------------------------------------------------
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elseif(TotAngMomBra(2) == 0) then
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do i=1,2
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do j=1,3
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a1m(i,j) = AngMomBra(i,j)
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a1mm(i,j) = AngMomBra(i,j)
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enddo
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enddo
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! Loop over cartesian directions
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xyz = 0
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if (AngMomBra(1,1) > 0) then
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xyz = 1
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elseif(AngMomBra(1,2) > 0) then
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xyz = 2
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elseif(AngMomBra(1,3) > 0) then
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xyz = 3
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else
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write(*,*) 'xyz = 0 in VRR2e!'
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endif
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! End loop over cartesian directions
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a1m(1,xyz) = a1m(1,xyz) - 1
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a1mm(1,xyz) = a1mm(1,xyz) - 2
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if(AngMomBra(1,xyz) <= 0) then
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a1a2 = 0d0
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elseif(AngMomBra(1,xyz) == 1) then
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a1a2 = CenterZA(1,xyz)*VRR2e(m,a1m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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- fZ(1)*CenterY(1,2,xyz)*VRR2e(m+1,a1m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY)
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else
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a1a2 = CenterZA(1,xyz)*VRR2e(m,a1m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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- fZ(1)*CenterY(1,2,xyz)*VRR2e(m+1,a1m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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+ 0.5d0*dble(AngMomBra(1,xyz)-1)*ExpZi(1)*( &
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VRR2e(m,a1mm,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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- fZ(1)*VRR2e(m+1,a1mm,maxm,Om,ExpZi,ExpY,CenterZA,CenterY))
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endif
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!------------------------------------------------------------------------
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! 2nd vertical recurrence relation (5 terms): (a0|c+0)^m
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!------------------------------------------------------------------------
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else
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do i=1,2
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do j=1,3
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a2m(i,j) = AngMomBra(i,j)
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a2mm(i,j) = AngMomBra(i,j)
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a1m2m(i,j) = AngMomBra(i,j)
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enddo
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enddo
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! Loop over cartesian directions
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xyz = 0
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if (AngMomBra(2,1) > 0) then
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xyz = 1
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elseif(AngMomBra(2,2) > 0) then
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xyz = 2
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elseif(AngMomBra(2,3) > 0) then
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xyz = 3
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else
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write(*,*) 'xyz = 0 in VRR2e!'
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endif
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! End loop over cartesian directions
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a2m(2,xyz) = a2m(2,xyz) - 1
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a2mm(2,xyz) = a2mm(2,xyz) - 2
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a1m2m(1,xyz) = a1m2m(1,xyz) - 1
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a1m2m(2,xyz) = a1m2m(2,xyz) - 1
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if(AngMomBra(2,xyz) <= 0) then
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a1a2 = 0d0
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elseif(AngMomBra(2,xyz) == 1) then
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a1a2 = CenterZA(2,xyz)*VRR2e(m,a2m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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+ fZ(2)*CenterY(1,2,xyz)*VRR2e(m+1,a2m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY)
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else
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a1a2 = CenterZA(2,xyz)*VRR2e(m,a2m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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+ fZ(2)*CenterY(1,2,xyz)*VRR2e(m+1,a2m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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+ 0.5d0*dble(AngMomBra(2,xyz)-1)*ExpZi(2)*( &
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VRR2e(m,a2mm,maxm,Om,ExpZi,ExpY,CenterZA,CenterY) &
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- fZ(2)*VRR2e(m+1,a2mm,maxm,Om,ExpZi,ExpY,CenterZA,CenterY))
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endif
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if(AngMomBra(1,xyz) > 0) &
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a1a2 = a1a2 &
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+ 0.5d0*dble(AngMomBra(1,xyz))*fZ(2)*ExpZi(1)*VRR2e(m+1,a1m2m,maxm,Om,ExpZi,ExpY,CenterZA,CenterY)
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endif
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end function VRR2e
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