mirror of https://gitlab.com/QEF/q-e.git
147 lines
4.3 KiB
Fortran
147 lines
4.3 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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subroutine gen_us_dj (ik, dvkb)
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!----------------------------------------------------------------------
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!
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! Calculates the beta function pseudopotentials with
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! the derivative of the Bessel functions
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!
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#include "machine.h"
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use pwcom
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implicit none
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!
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integer :: ik
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complex(kind=DP) :: dvkb (npwx, nkb)
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!
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! local variables
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!
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integer :: ikb, nb, ih, ig, i0, nt
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! counter on beta functions
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! counter on beta functions
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! counter on beta functions
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! counter on G vectors
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! index of the first nonzero point in the r
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! counter on atomic type
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real(kind=DP) :: arg
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! argument of the atomic phase factor
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complex(kind=DP) :: phase, pref
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! atomic phase factor
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! prefactor
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integer :: na, i, m, l, iig, lm
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real(kind=DP), allocatable :: djl (:,:,:), ylm (:,:), q (:), gk (:,:)
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real(kind=DP) :: jl (ndm), jlm1 (ndm), qt, dv, eps
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parameter (eps = 1.0e-8)
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complex(kind=DP), allocatable :: sk (:)
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if (nkb.eq.0) return
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allocate (djl( npw , nbrx , ntyp))
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allocate (ylm( npw ,(lmaxkb + 1) **2))
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allocate (gk( 3, npw))
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allocate (q( npw))
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do ig = 1, npw
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gk (1,ig) = xk (1, ik) + g(1, igk(ig) )
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gk (2,ig) = xk (2, ik) + g(2, igk(ig) )
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gk (3,ig) = xk (3, ik) + g(3, igk(ig) )
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q (ig) = gk(1, ig)**2 + gk(2, ig)**2 + gk(3, ig)**2
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enddo
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call ylmr2 ((lmaxkb+1)**2, npw, gk, q, ylm)
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do nt = 1, ntyp
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do nb = 1, nbeta (nt)
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l = lll (nb, nt)
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do ig = 1, npw
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qt = sqrt(q (ig)) * tpiba
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if (qt.lt.eps) then
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if (l.ne.1) then
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do i = 1, kkbeta (nt)
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jl (i) = 0.0d0
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enddo
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else
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! Note that dj_1/dx (x=0) = 1/3
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do i = 1, kkbeta (nt)
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jl (i) = 1.0d0 / 3.d0
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enddo
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endif
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else
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!
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! in order to avoid a division by zero i0 is defined as
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! the first point in the radial mesh such that q*r>eps
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! NB: eps value must be consistent with its value in sph_bes
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!
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i0 = 1
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do while ( qt * r(i0,nt) .lt. eps )
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i0 = i0 + 1
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end do
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call sph_bes (kkbeta(nt)+1-i0, r(i0, nt), qt, l, jl (i0))
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call sph_bes (kkbeta(nt)+1-i0, r(i0, nt), qt, l - 1, jlm1(i0) )
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! recurrence relation for jl
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do i = i0, kkbeta (nt)
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jl (i) = jlm1 (i) - (l + 1) / (qt * r (i, nt) ) * jl (i)
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enddo
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if (i0.eq.2) jl (1) = jl (2)
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endif
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! jl is now the derivative of the Bessel functions
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do i = 1, kkbeta (nt)
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jlm1 (i) = jl (i) * betar (i, nb, nt) * r (i, nt) **2
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enddo
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call simpson (kkbeta (nt), jlm1, rab (1, nt), dv)
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djl (ig, nb, nt) = dv * fpi / sqrt (omega)
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enddo
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enddo
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enddo
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deallocate (q)
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deallocate (gk)
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allocate (sk( npw))
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ikb = 0
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do nt = 1, ntyp
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do na = 1, nat
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if (ityp (na) .eq.nt) then
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arg = (xk (1, ik) * tau(1,na) + &
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xk (2, ik) * tau(2,na) + &
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xk (3, ik) * tau(3,na) ) * tpi
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phase = DCMPLX (cos (arg), - sin (arg) )
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do ig = 1, npw
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iig = igk (ig)
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sk (ig) = eigts1 (ig1 (iig), na) * &
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eigts2 (ig2 (iig), na) * &
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eigts3 (ig3 (iig), na) * phase
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enddo
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do ih = 1, nh (nt)
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nb = indv (ih, nt)
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l = nhtol (ih, nt)
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m = nhtom (ih, nt)
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lm = l * l + m
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ikb = ikb + 1
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pref = (0.d0, - 1.d0) **l
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!
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do ig = 1, npw
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dvkb (ig, ikb) = djl (ig, nb, nt) * sk (ig) * ylm (ig, lm) &
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* pref
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enddo
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enddo
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endif
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enddo
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enddo
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if (ikb.ne.nkb) call errore ('gen_us_dj', 'unexpected error', 1)
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deallocate (sk)
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deallocate (ylm)
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deallocate (djl)
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return
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end subroutine gen_us_dj
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