mirror of https://gitlab.com/QEF/q-e.git
153 lines
5.4 KiB
Fortran
153 lines
5.4 KiB
Fortran
!
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! Copyright (C) 2003 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 dgradcor1 (dfft, rho, grho, dvxc_rr, dvxc_sr, dvxc_ss, dvxc_s, &
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drho, drhoc, nspin, g, dvxc)
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! ===================
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!--------------------------------------------------------------------
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! ADD Gradient Correction contibution to screening potential
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! phonon calculation, half G-vectors
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USE kinds, ONLY : DP
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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
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REAL(DP), INTENT(IN) :: rho (dfft%nnr, nspin), grho (3, dfft%nnr, nspin), &
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g (3, dfft%ngm)
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REAL(DP), INTENT(OUT):: drho (dfft%nnr,nspin),&
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dvxc_rr(dfft%nnr, nspin, nspin), dvxc_sr (dfft%nnr, nspin, nspin), &
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dvxc_ss (dfft%nnr,nspin, nspin), dvxc_s (dfft%nnr, nspin, nspin)
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REAL(DP), INTENT(INOUT) :: dvxc (dfft%nnr, nspin)
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COMPLEX(DP) :: drhoc(dfft%nnr, nspin)
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!
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INTEGER :: k, ipol, is, js, ks, ls
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real(DP) :: epsr, epsg, grho2
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COMPLEX(DP) :: s1
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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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REAL(DP), ALLOCATABLE :: gdrho (:,:,:)
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REAL(DP), ALLOCATABLE :: h (:,:,:), dh (:)
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PARAMETER (epsr = 1.0d-6, epsg = 1.0d-10)
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ALLOCATE (gdrho( 3, dfft%nnr , nspin))
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ALLOCATE (h( 3, dfft%nnr , nspin))
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ALLOCATE (dh( dfft%nnr))
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h (:,:,:) = 0.d0
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DO is = 1, nspin
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CALL fft_gradient_g2r (dfft, drhoc(1, is), g, gdrho (1,1,is) )
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ENDDO
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DO k = 1, dfft%nnr
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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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grho2 = grho(1, k, 1)**2 + grho(2, k, 1)**2 + grho(3, k, 1)**2
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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, nspin
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DO js = 1, nspin
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DO ipol = 1, 3
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ps1(ipol, is, js) = drho (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, nspin
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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, nspin
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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, nspin
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DO js = 1, nspin
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dvxc (k, is) = dvxc (k, is) + dvxc_rr (k, is, js) * drho (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, nspin
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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, nspin
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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, nspin
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CALL fft_graddot (dfft, h (1, 1, is), 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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DEALLOCATE (dh)
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DEALLOCATE (h)
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DEALLOCATE (gdrho)
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RETURN
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END SUBROUTINE dgradcor1
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