mirror of https://gitlab.com/QEF/q-e.git
145 lines
4.3 KiB
Fortran
145 lines
4.3 KiB
Fortran
!
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! Copyright (C) 2001-2008 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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!-----------------------------------------------------------------------
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subroutine polariz ( iw, iu )
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!-----------------------------------------------------------------------
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!
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! calculates the frequency dependent polarizability
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!
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USE io_global, ONLY : stdout
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USE io_files, ONLY : iunigk
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USE constants, ONLY : fpi
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USE cell_base, ONLY : at, bg, omega
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USE klist, ONLY : wk
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USE symme, ONLY : symmatrix, crys_to_cart
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USE wvfct, ONLY : npw, npwx, igk
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USE kinds, ONLY : DP
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USE control_lr, ONLY : nbnd_occ
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USE units_ph, ONLY : lrdwf, iudwf, lrebar, iuebar
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USE buffers, ONLY : get_buffer
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USE freq_ph, ONLY : polar, done_iu, comp_iu
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USE eqv, ONLY : dpsi, dvpsi
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USE qpoint, ONLY : nksq
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USE ph_restart, ONLY : ph_writefile
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USE cell_base, ONLY : omega
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USE mp_pools, ONLY : inter_pool_comm
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USE mp_bands, ONLY : intra_bgrp_comm
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USE mp, ONLY : mp_sum
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!
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IMPLICIT NONE
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!
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! I/O variables
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!
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REAL(kind=DP) :: iw
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!
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INTEGER, INTENT(IN) :: iu
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!
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! local variables
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!
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integer :: ibnd, ipol, jpol, nrec, ik, ierr
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! counter on polarizations
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! counter on records
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! counter on k points
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real(kind=DP) :: w, weight, repsilon(3,3)
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complex(kind=DP), EXTERNAL :: zdotc
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call start_clock ('polariz')
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repsilon(:,:) = 0.d0
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if (nksq > 1) rewind (unit = iunigk)
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do ik = 1, nksq
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if (nksq > 1) read (iunigk) npw, igk
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weight = wk (ik)
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w = fpi * weight / omega
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do ipol = 1, 3
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nrec = (ipol - 1) * nksq + ik
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call get_buffer (dvpsi, lrebar, iuebar, nrec)
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do jpol = 1, 3
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nrec = (jpol - 1) * nksq + ik
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call get_buffer(dpsi, lrdwf, iudwf, nrec)
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do ibnd = 1, nbnd_occ (ik)
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!
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! this is the real part of <DeltaV*psi(E)|DeltaPsi(E)>
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!
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repsilon(ipol,jpol)=repsilon(ipol,jpol)-4.d0*w*REAL( &
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zdotc (npw, dvpsi (1, ibnd), 1, dpsi (1, ibnd), 1) )
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enddo
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enddo
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enddo
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enddo
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call mp_sum ( repsilon, intra_bgrp_comm )
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call mp_sum ( repsilon, inter_pool_comm )
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!
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! symmetrize
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!
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! WRITE( stdout,'(/,10x,"Unsymmetrized in crystal axis ",/)')
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! WRITE( stdout,'(10x,"(",3f15.5," )")') ((repsilon(ipol,jpol),
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! + ipol=1,3),jpol=1,3)
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call crys_to_cart ( repsilon )
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call symmatrix ( repsilon )
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!
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! pass to cartesian axis
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!
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! WRITE( stdout,'(/,10x,"Symmetrized in cartesian axis ",/)')
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! WRITE( stdout,'(10x,"(",3f15.5," )")') ((repsilon(ipol,jpol),
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! + ipol=1,3),jpol=1,3)
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!
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! add the diagonal part
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!
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do ipol = 1, 3
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repsilon (ipol, ipol) = repsilon (ipol, ipol) + 1.d0
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enddo
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!
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! compute the polarization
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!
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do ipol = 1, 3
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do jpol = 1, 3
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if ( repsilon (ipol, jpol) .gt. 1.d-4 ) &
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repsilon (ipol, jpol) = (3.d0*omega/fpi) * ( repsilon (ipol, jpol) - 1.d0 ) / &
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( repsilon (ipol, jpol) + 2.d0 )
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enddo
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enddo
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!
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! and print the result
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!
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WRITE( stdout, '(/,10x,"Polarizability in cartesian axis at frequency ",f5.2,/)') iw
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WRITE( stdout, '(10x,"(",3f18.9," )")') ((repsilon(ipol,jpol), ipol=1,3), jpol=1,3)
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polar(:,:,iu)=repsilon(:,:)
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CALL write_polariz(iu)
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done_iu(iu)=.TRUE.
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call ph_writefile('polarization',0,iu,ierr)
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!
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call stop_clock ('polariz')
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return
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end subroutine polariz
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SUBROUTINE write_polariz(iu)
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!
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! This routine write on output the
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!
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USE io_global, ONLY : stdout
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USE constants, ONLY : BOHR_RADIUS_ANGS
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USE freq_ph, ONLY : fiu, polar
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IMPLICIT NONE
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INTEGER, INTENT(IN) :: iu
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INTEGER :: ipol, jpol
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WRITE(stdout,'(2(/),30x," Frequency ",f10.5, "i Ry" )') fiu(iu)
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WRITE(stdout,'(2(/),30x," Cartesian axis " )')
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WRITE(stdout,'(/,5x,"Polarizability (a.u.)^3",20x,"Polarizability (A^3)")')
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WRITE(stdout,'(3f10.2,5x,3f14.4)') ( (polar(ipol,jpol,iu), jpol=1,3), &
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(polar(ipol,jpol,iu)*BOHR_RADIUS_ANGS**3, jpol=1,3), ipol=1,3)
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RETURN
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END SUBROUTINE write_polariz
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