mirror of https://gitlab.com/QEF/q-e.git
239 lines
8.2 KiB
Fortran
239 lines
8.2 KiB
Fortran
!
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! Copyright (C) 2001-2016 Quantum ESPRESSO 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 dgradcorr (dfft, rho, grho, dvxc_rr, dvxc_sr, dvxc_ss, &
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dvxc_s, xq, drho, nspin, nspin0, g, dvxc)
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!--------------------------------------------------------------------
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!
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! Add gradient correction contribution to
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! the response exchange-correlation potential dvxc.
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! LSDA is allowed. ADC (September 1999)
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! Noncollinear is allowed. ADC (June 2007)
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!
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USE kinds, ONLY : DP
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USE noncollin_module, ONLY : noncolin, domag
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USE gc_lr, ONLY : gmag, vsgga, segni
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USE fft_types, ONLY : fft_type_descriptor
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!
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IMPLICIT NONE
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!
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TYPE(fft_type_descriptor),INTENT(IN) :: dfft
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INTEGER, INTENT(IN) :: nspin, nspin0
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!
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REAL(DP), INTENT(IN) ::rho (dfft%nnr, nspin), grho (3, dfft%nnr, nspin0), &
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g (3, dfft%ngm), xq(3)
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REAL(DP), INTENT(IN) :: &
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dvxc_rr(dfft%nnr, nspin0, nspin0), dvxc_sr (dfft%nnr, nspin0, nspin0), &
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dvxc_ss (dfft%nnr,nspin0, nspin0), dvxc_s (dfft%nnr, nspin0, nspin0)
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COMPLEX(DP), INTENT(IN) :: drho (dfft%nnr, nspin)
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COMPLEX(DP), INTENT(INOUT) :: dvxc (dfft%nnr, nspin)
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real(DP), parameter :: epsr = 1.0d-6, epsg = 1.0d-10
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real(DP) :: grho2, seg, seg0, amag
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complex(DP) :: s1, fact, term
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complex(DP) :: a (2, 2, 2), b (2, 2, 2, 2), c (2, 2, 2), &
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ps (2, 2), ps1 (3, 2, 2), ps2 (3, 2, 2, 2)
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complex(DP), allocatable :: gdrho (:,:,:), h (:,:,:), dh (:)
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complex(DP), allocatable :: gdmag (:,:,:), dvxcsave(:,:), vgg(:,:)
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complex(DP), allocatable :: drhoout(:,:)
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integer :: k, ipol, jpol, is, js, ks, ls
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IF ( nspin < nspin0 .OR. nspin < 1 .OR. nspin > 4 ) &
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CALL errore('dgradcorr', 'incorrect number of spin components',1)
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if (noncolin.and.domag) then
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allocate (gdmag(3, dfft%nnr, nspin))
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allocate (dvxcsave(dfft%nnr, nspin))
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allocate (vgg(dfft%nnr, nspin0))
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dvxcsave=dvxc
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dvxc=(0.0_dp,0.0_dp)
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endif
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allocate (drhoout( dfft%nnr, nspin0))
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allocate (gdrho( 3, dfft%nnr, nspin0))
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allocate (h( 3, dfft%nnr, nspin0))
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allocate (dh( dfft%nnr))
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h (:, :, :) = (0.d0, 0.d0)
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if (noncolin.and.domag) then
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do is = 1, nspin
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call fft_qgradient (dfft, drho(1,is), xq, g, gdmag (1, 1, is) )
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enddo
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DO is=1,nspin0
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IF (is==1) seg0=0.5_dp
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IF (is==2) seg0=-0.5_dp
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drhoout(:,is) = 0.5_dp*drho(:,1)
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DO ipol=1,3
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gdrho(ipol,:,is) = 0.5_dp*gdmag(ipol,:,1)
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ENDDO
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DO k=1,dfft%nnr
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seg=seg0*segni(k)
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amag=sqrt(rho(k,2)**2+rho(k,3)**2+rho(k,4)**2)
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IF (amag>1.d-12) THEN
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DO jpol=2,4
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drhoout(k,is) = drhoout(k,is)+seg*rho(k,jpol)* &
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drho(k,jpol)/amag
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END DO
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DO ipol=1,3
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fact=(0.0_dp,0.0_dp)
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DO jpol=2,4
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fact=fact+rho(k,jpol)*drho(k,jpol)
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END DO
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DO jpol=2,4
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gdrho(ipol,k,is) = gdrho(ipol,k,is)+ seg*( &
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drho(k,jpol)*gmag(ipol,k,jpol)+ &
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rho(k,jpol)*gdmag(ipol,k,jpol))/amag &
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-seg*(rho(k,jpol)*gmag(ipol,k,jpol)*fact)/amag**3
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END DO
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END DO
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END IF
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END DO
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END DO
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ELSE
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!
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DO is = 1, nspin0
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CALL fft_qgradient (dfft, drho(1,is), xq, g, gdrho (1, 1, is) )
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drhoout(:,is)=drho(:,is)
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ENDDO
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!
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ENDIF
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do k = 1, dfft%nnr
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grho2 = grho(1, k, 1)**2 + grho(2, k, 1)**2 + grho(3, k, 1)**2
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if (nspin == 1) then
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!
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! LDA case
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!
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if (abs (rho (k, 1) ) > epsr .and. grho2 > epsg) then
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s1 = grho (1, k, 1) * gdrho (1, k, 1) + &
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grho (2, k, 1) * gdrho (2, k, 1) + &
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grho (3, k, 1) * gdrho (3, k, 1)
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!
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! linear variation of the first term
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!
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dvxc (k, 1) = dvxc (k, 1) + dvxc_rr (k, 1, 1) * drho (k, 1) &
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+ dvxc_sr (k, 1, 1) * s1
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do ipol = 1, 3
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h (ipol, k, 1) = (dvxc_sr(k, 1, 1) * drho(k, 1) + &
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dvxc_ss(k, 1, 1) * s1 )*grho(ipol, k, 1) + &
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dvxc_s (k, 1, 1) * gdrho (ipol, k, 1)
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enddo
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else
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do ipol = 1, 3
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h (ipol, k, 1) = (0.d0, 0.d0)
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enddo
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endif
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else
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!
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! LSDA case
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!
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ps (:,:) = (0.d0, 0.d0)
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do is = 1, nspin0
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do js = 1, nspin0
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do ipol = 1, 3
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ps1(ipol, is, js) = drhoout (k, is) * grho (ipol, k, js)
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ps(is, js) = ps(is, js) + grho(ipol,k,is)*gdrho(ipol,k,js)
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enddo
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do ks = 1, nspin0
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if (is == js .and. js == ks) then
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a (is, js, ks) = dvxc_sr (k, is, is)
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c (is, js, ks) = dvxc_sr (k, is, is)
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else
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if (is == 1) then
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a (is, js, ks) = dvxc_sr (k, 1, 2)
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else
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a (is, js, ks) = dvxc_sr (k, 2, 1)
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endif
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if (js == 1) then
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c (is, js, ks) = dvxc_sr (k, 1, 2)
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else
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c (is, js, ks) = dvxc_sr (k, 2, 1)
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endif
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endif
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do ipol = 1, 3
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ps2 (ipol, is, js, ks) = ps (is, js) * grho (ipol, k, ks)
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enddo
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do ls = 1, nspin0
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if (is == js .and. js == ks .and. ks == ls) then
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b (is, js, ks, ls) = dvxc_ss (k, is, is)
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else
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if (is == 1) then
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b (is, js, ks, ls) = dvxc_ss (k, 1, 2)
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else
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b (is, js, ks, ls) = dvxc_ss (k, 2, 1)
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endif
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endif
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enddo
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enddo
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enddo
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enddo
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do is = 1, nspin0
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do js = 1, nspin0
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dvxc (k, is) = dvxc (k, is) + dvxc_rr (k,is,js)*drhoout(k, js)
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do ipol = 1, 3
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h (ipol, k, is) = h (ipol, k, is) + &
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dvxc_s (k, is, js) * gdrho(ipol, k, js)
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enddo
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do ks = 1, nspin0
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dvxc (k, is) = dvxc (k, is) + a (is, js, ks) * ps (js, ks)
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do ipol = 1, 3
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h (ipol, k, is) = h (ipol, k, is) + &
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c (is, js, ks) * ps1 (ipol, js, ks)
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enddo
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do ls = 1, nspin0
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do ipol = 1, 3
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h (ipol, k, is) = h (ipol, k, is) + &
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b (is, js, ks, ls) * ps2 (ipol, js, ks, ls)
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enddo
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enddo
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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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! linear variation of the second term
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do is = 1, nspin0
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call fft_qgraddot (dfft, h (1, 1, is), xq, g, dh)
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do k = 1, dfft%nnr
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dvxc (k, is) = dvxc (k, is) - dh (k)
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enddo
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enddo
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IF (noncolin.AND.domag) THEN
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DO is=1,nspin0
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vgg(:,is)=dvxc(:,is)
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ENDDO
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dvxc=dvxcsave
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DO k=1,dfft%nnr
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dvxc(k,1)=dvxc(k,1)+0.5d0*(vgg(k,1)+vgg(k,2))
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amag=sqrt(rho(k,2)**2+rho(k,3)**2+rho(k,4)**2)
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IF (amag.GT.1.d-12) THEN
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DO is=2,4
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term=(0.0_dp,0.0_dp)
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DO jpol=2,4
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term=term+rho(k,jpol)*drho(k,jpol)
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ENDDO
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term=term*rho(k,is)/amag**2
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dvxc(k,is)=dvxc(k,is)+0.5d0*segni(k)*((vgg(k,1)-vgg(k,2)) &
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*rho(k,is)+vsgga(k)*(drho(k,is)-term))/amag
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ENDDO
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ENDIF
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ENDDO
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ENDIF
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deallocate (dh)
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deallocate (h)
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deallocate (gdrho)
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deallocate (drhoout)
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if (noncolin.and.domag) then
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deallocate (gdmag)
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deallocate (dvxcsave)
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deallocate (vgg)
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endif
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return
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end subroutine dgradcorr
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