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https://github.com/pfloos/quack
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51 lines
996 B
Fortran
51 lines
996 B
Fortran
subroutine drift(nWalk,r,r12,g,dg,F)
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! Compute quantum force
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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) :: nWalk
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double precision,intent(in) :: r(nWalk,2,3),r12(nWalk),g(nWalk,2),dg(nWalk,2,3)
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! Local variables
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logical :: smoothDrift
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double precision :: rij,rijSq,w,wSq,damp
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integer :: iW
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! Output variables
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double precision,intent(out) :: F(nWalk,2,3)
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! Compute
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smoothDrift = .false.
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w = 0.1d0
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wSq = w*w
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do iW=1,nWalk
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rij = r12(iW)
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rijSq = rij*rij
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F(iW,1,1:3) = dg(iW,1,1:3)/g(iW,1)
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F(iW,2,1:3) = dg(iW,2,1:3)/g(iW,2)
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if(smoothDrift) then
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damp = 1d0 + 2d0*w/sqrt(pi)*rij*exp(-wSq*rijSq)/erfc(w*rij)
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else
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damp = 1d0
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endif
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F(iW,1,1:3) = F(iW,1,1:3) - damp*(r(iW,2,1:3) - r(iW,1,1:3))/rijSq
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F(iW,2,1:3) = F(iW,2,1:3) - damp*(r(iW,2,1:3) - r(iW,1,1:3))/rijSq
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enddo
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! print*,' F',F
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end subroutine drift
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