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https://github.com/pfloos/quack
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42 lines
907 B
Fortran
42 lines
907 B
Fortran
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subroutine transition_probability(nWalk,dt,D,r,rp,F,Fp,T,Tp)
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! Compute transition probability
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implicit none
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! Input variables
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integer,intent(in) :: nWalk
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double precision,intent(in) :: dt,D
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double precision,intent(in) :: r(nWalk,1:2,1:3), F(nWalk,1:2,1:3)
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double precision,intent(in) :: rp(nWalk,1:2,1:3),Fp(nWalk,1:2,1:3)
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! Local variables
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integer :: iW,iEl,ixyz
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! Output variables
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double precision,intent(out) :: T(nWalk),Tp(nWalk)
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! Initialize
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T = 0d0
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Tp = 0d0
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! Compute
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do iW=1,nWalk
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do iEl=1,2
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do ixyz=1,3
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T(iW) = T(iW) + (rp(iW,iEl,ixyz) - r(iW,iEl,ixyz) - D*dt*F(iW,iEl,ixyz))**2
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Tp(iW) = Tp(iW) + (r(iW,iEl,ixyz) - rp(iW,iEl,ixyz) - D*dt*Fp(iW,iEl,ixyz))**2
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enddo
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enddo
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enddo
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T(:) = exp(-0.25d0*T(:)/(D*dt))
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Tp(:) = exp(-0.25d0*Tp(:)/(D*dt))
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end subroutine transition_probability
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