mirror of https://github.com/pfloos/quack
141 lines
3.6 KiB
Fortran
141 lines
3.6 KiB
Fortran
function G2eInt(debug,iType, &
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ExpG, &
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ExpBra,CenterBra,AngMomBra, &
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ExpKet,CenterKet,AngMomKet)
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! Compute recursively the primitive two-electron integral [ab|cd]
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implicit none
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include 'parameters.h'
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! Input variables
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logical,intent(in) :: debug
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integer,intent(in) :: iType
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double precision,intent(in) :: ExpBra(2),ExpKet(2)
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double precision,intent(in) :: ExpG
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double precision,intent(in) :: CenterBra(2,3),CenterKet(2,3)
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integer,intent(in) :: AngMomBra(2,3),AngMomKet(2,3)
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! Local variables
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integer :: TotAngMomBra(3),TotAngMomKet(3)
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double precision :: ExpZi(2),ExpY(2,2)
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double precision :: CenterZ(2,3),CenterAB(2,3),CenterZA(2,3),CenterY(2,2,3)
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double precision :: NormABSq(2),NormYSq(2,2)
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double precision :: GAB(2)
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double precision,allocatable :: Om(:)
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double precision :: fG
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double precision :: HRR2e,VRR2e
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double precision :: a1a2b1b2
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integer :: i,j,k,maxm
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double precision :: start_Om,finish_Om,start_RR,finish_RR,t_Om,t_RR
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! Output variables
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double precision :: G2eInt
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! Pre-computed shell-pair quantities
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do i=1,2
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ExpZi(i) = 1d0/(ExpBra(i) + ExpKet(i))
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enddo
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NormABSq = 0d0
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do j=1,3
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do i=1,2
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CenterZ(i,j) = (ExpBra(i)*CenterBra(i,j) + ExpKet(i)*CenterKet(i,j))*ExpZi(i)
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CenterAB(i,j) = CenterBra(i,j) - CenterKet(i,j)
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CenterZA(i,j) = CenterZ(i,j) - CenterBra(i,j)
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NormABSq(i) = NormABSq(i) + CenterAB(i,j)**2
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enddo
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enddo
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do i=1,2
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GAB(i) = (pi*ExpZi(i))**(1.5d0)*exp(-ExpBra(i)*ExpKet(i)*NormABSq(i)*ExpZi(i))
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enddo
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! Pre-computed shell-quartet quantities
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do i=1,2
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do j=1,2
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ExpY(i,j) = 1d0/(ExpZi(i) + ExpZi(j))
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enddo
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enddo
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do i=1,2
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do j=1,2
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NormYSq(i,j) = 0d0
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do k=1,3
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CenterY(i,j,k) = CenterZ(i,k) - CenterZ(j,k)
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NormYSq(i,j) = NormYSq(i,j) + CenterY(i,j,k)**2
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enddo
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enddo
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enddo
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! fG = (ExpZ(1)*ExpZ(2)*ExpG)/(ExpZ(1)*ExpZ(2) + ExpZ(1)*ExpG + ExpZ(2)*ExpG)
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fG = 1d0/(ExpZi(1) + 1d0/ExpG + ExpZi(2))
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! Total angular momemtum
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maxm = 0
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do i=1,2
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TotAngMomBra(i) = AngMomBra(i,1) + AngMomBra(i,2) + AngMomBra(i,3)
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TotAngMomKet(i) = AngMomKet(i,1) + AngMomKet(i,2) + AngMomKet(i,3)
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maxm = maxm + TotAngMomBra(i) + TotAngMomKet(i)
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enddo
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! Pre-compute (00|00)^m
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allocate(Om(0:maxm))
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call cpu_time(start_Om)
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if(iType == 1) then
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call CalcOmERI(maxm,ExpY(1,2),NormYSq(1,2),Om)
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elseif(iType == 3) then
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call CalcOmYuk(maxm,ExpG,ExpY(1,2),fG,NormYSq(1,2),Om)
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elseif(iType == 4) then
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call CalcOmErf(maxm,ExpY(1,2),fG,NormYSq(1,2),Om)
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endif
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call cpu_time(finish_Om)
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! Print (00|00)^m
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if(debug) then
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write(*,*) '(00|00)^m'
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do i=0,maxm
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write(*,*) i,Om(i)
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enddo
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write(*,*)
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endif
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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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if(TotAngMomKet(1) == 0 .and. TotAngMomKet(2) == 0) then
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if(TotAngMomBra(1) == 0 .and. TotAngMomBra(2) == 0) then
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a1a2b1b2 = Om(0)
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else
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a1a2b1b2 = VRR2e(0,AngMomBra,maxm,Om,ExpZi,ExpY,CenterZA,CenterY)
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endif
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else
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a1a2b1b2 = HRR2e(AngMomBra,AngMomKet,maxm,Om,ExpZi,ExpY,CenterAB,CenterZA,CenterY)
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endif
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call cpu_time(finish_RR)
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! Timings
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t_Om = finish_Om - start_Om
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t_RR = finish_RR - start_RR
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! Print result
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G2eInt = GAB(1)*GAB(2)*a1a2b1b2
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end function G2eInt
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