mirror of https://gitlab.com/QEF/q-e.git
216 lines
7.5 KiB
Fortran
216 lines
7.5 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 addusddens (drhoscf, dbecsum, mode0, npe, iflag)
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!----------------------------------------------------------------------
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!! This routine adds to the change of the charge and of the
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!! magnetization densities the part due to the US augmentation.
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!! It assumes that the array dbecsum has already accumulated the
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!! change of the becsum term. It calculates Eq. B31 of Ref [1].
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!! If called from drho (iflag=1), dbecsum and drhoscf contain the
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!! orthogonalization contribution to the change of the wavefunctions
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!! and the terms with alphasum and becsum are added. If called
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!! from solve_* (iflag=0) drhoscf and dbecsum contain the contribution
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!! of the solution of the linear system and the terms due to alphasum
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!! and becsum are not added. In this case the change of the charge
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!! calculated by drho (called \(\Delta \rho\) in [1]) is read from file
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!! and added. The contribution of the change of
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!! the Fermi energy is not calculated here but added later by ef_shift.
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!! [1] PRB 64, 235118 (2001).
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!
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!
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USE kinds, only : DP
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use fft_base, only: dfftp
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use fft_interfaces, only: invfft
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USE gvect, ONLY : gg, ngm, g, eigts1, eigts2, eigts3, mill
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USE uspp, ONLY : okvan, becsum
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USE cell_base, ONLY : tpiba
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USE ions_base, ONLY : nat, ityp, ntyp => nsp
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USE wavefunctions, ONLY: psic
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USE buffers, ONLY : get_buffer
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USE uspp_param, ONLY: upf, lmaxq, nh, nhm
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USE paw_variables, ONLY : okpaw
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USE modes, ONLY : u
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USE phus, ONLY : becsumort, alphasum
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USE units_ph, ONLY : iudrhous, lrdrhous
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USE noncollin_module, ONLY : nspin_mag
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USE qpoint, ONLY : xq, eigqts
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USE control_lr, ONLY : lgamma
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implicit none
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!
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! the dummy variables
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!
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integer :: iflag
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!! input: if zero does not compute drho
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integer :: npe
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!! input: the number of perturbations
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complex(DP) :: drhoscf (dfftp%nnr, nspin_mag, npe)
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!! inp/out: change of the charge density
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complex(DP) :: dbecsum (nhm*(nhm+1)/2, nat, nspin_mag, npe)
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!! input: sum over kv of bec
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integer :: mode0
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!! input:the mode of the representation
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!
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! here the local variables
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!
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integer :: ig, na, nt, ih, jh, mu, mode, ipert, is, ijh
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! counter on G vectors
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! counter on atoms
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! counter on atomic type
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! counter on beta functions
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! counter on beta functions
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! counter on r vectors
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! pointer on modes
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! pointer on the mode
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! counter on perturbations
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! counter on spin
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! counter on combined beta functions
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real(DP), allocatable :: qmod (:), qpg (:,:), ylmk0 (:,:)
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! the modulus of q+G
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! the values of q+G
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! the spherical harmonics
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complex(DP) :: fact, zsum, bb, alpha, alpha_0, u1, u2, u3
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! auxiliary variables
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complex(DP), allocatable :: sk (:), qgm(:), drhous (:,:), aux (:,:,:)
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! the structure factor
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! q_lm(G)
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! contain the charge of drho
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! auxiliary variable for drho(G)
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if (.not.okvan) return
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call start_clock ('addusddens')
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allocate (aux( ngm , nspin_mag , npe))
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allocate (sk ( ngm))
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allocate (ylmk0(ngm , lmaxq * lmaxq))
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allocate (qgm( ngm))
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allocate (qmod( ngm))
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if (.not.lgamma) allocate (qpg( 3 , ngm))
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! WRITE( stdout,*) aux, ylmk0, qmod
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!
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! And then we compute the additional charge in reciprocal space
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!
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if (.not.lgamma) then
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call setqmod (ngm, xq, g, qmod, qpg)
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call ylmr2 (lmaxq * lmaxq, ngm, qpg, qmod, ylmk0)
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do ig = 1, ngm
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qmod (ig) = sqrt (qmod (ig) ) * tpiba
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enddo
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else
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call ylmr2 (lmaxq * lmaxq, ngm, g, gg, ylmk0)
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do ig = 1, ngm
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qmod (ig) = sqrt (gg (ig) ) * tpiba
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enddo
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endif
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fact = cmplx (0.d0, - tpiba, kind=DP)
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aux(:,:,:) = (0.d0, 0.d0)
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do nt = 1, ntyp
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if (upf(nt)%tvanp ) then
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ijh = 0
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do ih = 1, nh (nt)
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do jh = ih, nh (nt)
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call qvan2 (ngm, ih, jh, nt, qmod, qgm, ylmk0)
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ijh = ijh + 1
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do na = 1, nat
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if (ityp (na) .eq.nt) then
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mu = 3 * (na - 1)
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!
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! calculate the structure factor
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!
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do ig = 1, ngm
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sk (ig) = eigts1 (mill(1,ig), na) * &
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eigts2 (mill(2,ig), na) * &
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eigts3 (mill(3,ig), na) * &
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eigqts (na) * qgm (ig)
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enddo
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!
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! And qgmq and becp and dbecq
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!
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do ipert = 1, npe
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do is = 1, nspin_mag
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mode = mode0 + ipert
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if (iflag==1) then
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zsum = dbecsum (ijh, na, is, ipert)
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else
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zsum = 2.0_DP*dbecsum (ijh, na, is, ipert)
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endif
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u1 = u (mu + 1, mode)
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u2 = u (mu + 2, mode)
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u3 = u (mu + 3, mode)
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if (abs(u1) + abs(u2) + abs(u3) .gt.1d-12 .and. &
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iflag.eq.1) then
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bb = becsum (ijh, na, is)
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zsum = zsum + &
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( alphasum (ijh, 1, na, is) * u1 &
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+ alphasum (ijh, 2, na, is) * u2 &
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+ alphasum (ijh, 3, na, is) * u3)
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IF (okpaw) becsumort(ijh,na,is,mode) = zsum
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u1 = u1 * fact
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u2 = u2 * fact
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u3 = u3 * fact
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alpha_0 = xq(1)*u1 + xq(2)*u2 + xq(3)*u3
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do ig = 1, ngm
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alpha = alpha_0 + &
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g(1,ig)*u1 + g(2,ig)*u2 + g(3,ig)*u3
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aux(ig,is,ipert) = aux(ig,is,ipert) + &
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(zsum + alpha*bb) * sk(ig)
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enddo
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else
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call zaxpy (ngm, zsum, sk, 1, aux(1,is,ipert), 1)
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IF (okpaw.and.iflag==1) &
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becsumort(ijh,na,is,mode) = zsum
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endif
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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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enddo
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endif
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enddo
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!
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! convert aux to real space
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!
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do ipert = 1, npe
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mu = mode0 + ipert
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do is = 1, nspin_mag
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psic(:) = (0.d0, 0.d0)
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do ig = 1, ngm
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psic (dfftp%nl (ig) ) = aux (ig, is, ipert)
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enddo
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CALL invfft ('Rho', psic, dfftp)
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call daxpy (2*dfftp%nnr, 1.0_DP, psic, 1, drhoscf(1,is,ipert), 1)
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enddo
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enddo
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if (.not.lgamma) deallocate (qpg)
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deallocate (qmod)
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deallocate (qgm)
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deallocate (ylmk0)
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deallocate (sk)
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deallocate (aux)
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if (iflag == 0) then
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allocate (drhous( dfftp%nnr, nspin_mag))
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do ipert = 1, npe
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mu = mode0 + ipert
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call get_buffer (drhous, lrdrhous, iudrhous, mu)
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call daxpy (2*dfftp%nnr*nspin_mag, 1.d0, drhous, 1, drhoscf(1,1,ipert), 1)
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end do
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deallocate (drhous)
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end if
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call stop_clock ('addusddens')
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return
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end subroutine addusddens
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