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61 lines
1.6 KiB
Fortran
61 lines
1.6 KiB
Fortran
BEGIN_PROVIDER [double precision, factor_een]
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implicit none
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BEGIN_DOC
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! Electron-electron nucleus contribution to Jastrow factor
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END_DOC
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integer :: i, j, alpha, p, k, l, lmax = 0
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double precision :: x, y, z, t, c_inv, u, a, b, a2, b2, c, t0
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PROVIDE cord_vect
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factor_een = 0.0d0
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do alpha = 1, nnuc
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do j = 1, nelec
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b = rescale_een_n(j, alpha)
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do i = 1, nelec
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u = rescale_een_e(i,j)
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a = rescale_een_n(i, alpha)
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a2 = a*a
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b2 = b*b
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c = rescale_een_n(i, alpha) * rescale_een_n(j, alpha)
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c_inv = 1.d0/c
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do p = 2, ncord
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x = 1.d0
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do k = 0, p - 1
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if ( k /= 0 ) then
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lmax = p - k
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else
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lmax = p - k - 2
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end if
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t = x
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do l=1,rshift(p - k,1)
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t = t*c
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end do
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! We have suppressed this from the following loop:
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! if ( iand(p - k - l, 1) == 0 ) then
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!
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! Start from l=0 when p-k is even
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! Start from l=1 when p-k is odd
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if (iand(p-k,1) == 0) then
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y = 1.d0
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z = 1.d0
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else
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y = a
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z = b
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endif
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do l = iand(p-k,1), lmax, 2
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factor_een = factor_een + cord_vect(l, k, p, alpha) * (y+z) * t
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t = t * c_inv
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y = y * a2
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z = z * b2
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end do
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x = x * u
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end do
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end do
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end do
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end do
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end do
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factor_een = 0.5d0 * factor_een
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END_PROVIDER
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