mirror of https://gitlab.com/QEF/q-e.git
53 lines
1.5 KiB
Fortran
53 lines
1.5 KiB
Fortran
!
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! Copyright (C) 2001 PWSCF group
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! This file is distributed under the terms of the
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! GNU General Public License. See the file `License'
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! in the root directory of the present distribution,
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! or http://www.gnu.org/copyleft/gpl.txt .
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!
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!
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!-----------------------------------------------------------------------
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subroutine n_plane_waves (ecutwfc, tpiba2, nks, nkstot, xk, g, ngm, &
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npwx, ngk)
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!-----------------------------------------------------------------------
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!
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! Find number of plane waves for each k-point
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!
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USE kinds
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implicit none
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! input
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integer :: nks, nkstot, ngm
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real(DP) :: ecutwfc, tpiba2, xk (3, nks), g (3, ngm)
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! output
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integer :: npwx, ngk (nkstot)
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! local
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integer :: nk, ng
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real(DP) :: q2
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!
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npwx = 0
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do nk = 1, nks
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ngk (nk) = 0
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do ng = 1, ngm
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q2 = (xk (1, nk) + g (1, ng) ) **2 + (xk (2, nk) + g (2, ng) ) ** &
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2 + (xk (3, nk) + g (3, ng) ) **2
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if (q2 <= ecutwfc / tpiba2) then
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!
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! here if |k+G|^2 <= Ecut increase the number of G inside the sphere
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!
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ngk (nk) = ngk (nk) + 1
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else
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if (sqrt (g (1, ng) **2 + g (2, ng) **2 + g (3, ng) **2) &
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.gt.sqrt (xk (1, nk) **2 + xk (2, nk) **2 + xk (3, nk) **2) &
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+ sqrt (ecutwfc / tpiba2) ) goto 100
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!
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! if |G| > |k| + sqrt(Ecut) stop search
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!
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endif
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enddo
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100 npwx = max (npwx, ngk (nk) )
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enddo
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if (npwx <= 0) call errore ('n_plane_waves', 'No PWs !', 1)
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return
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end subroutine n_plane_waves
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