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!
! Copyright (C) 2001-2008 Quantum ESPRESSO group
! This file is distributed under the terms of the
! GNU General Public License. See the file `License'
! in the root directory of the present distribution,
! or http://www.gnu.org/copyleft/gpl.txt .
!
!----------------------------------------------------------------------------
PROGRAM q2r
!----------------------------------------------------------------------------
!
! q2r.x:
! reads force constant matrices C(q) produced by the phonon code
! for a grid of q-points, calculates the corresponding set of
! interatomic force constants (IFC), C(R)
!
! Input data: Namelist "input"
! fildyn : input file name (character, must be specified)
! "fildyn"0 contains information on the q-point grid
! "fildyn"1-N contain force constants C_n = C(q_n)
! for n=1,...N, where N is the number of q-points
! in the irreducible brillouin zone
! Normally this should be the same as specified
! on input to the phonon code
! In the non collinear/spin-orbit case the files
! produced by ph.x are in .xml format. In this case
! fildyn is the same as in the phonon code + the .xml
! extension.
! flfrc : output file containing the IFC in real space
! (character, must be specified)
! zasr : Indicates type of Acoustic Sum Rules used for the Born
! effective charges (character):
! - 'no': no Acoustic Sum Rules imposed (default)
! - 'simple': previous implementation of the asr used
! (3 translational asr imposed by correction of
! the diagonal elements of the force-constants matrix)
! - 'crystal': 3 translational asr imposed by optimized
! correction of the IFC (projection).
! - 'one-dim': 3 translational asr + 1 rotational asr
! imposed by optimized correction of the IFC (the
! rotation axis is the direction of periodicity; it
! will work only if this axis considered is one of
! the cartesian axis).
! - 'zero-dim': 3 translational asr + 3 rotational asr
! imposed by optimized correction of the IFC.
! Note that in certain cases, not all the rotational asr
! can be applied (e.g. if there are only 2 atoms in a
! molecule or if all the atoms are aligned, etc.).
! In these cases the supplementary asr are cancelled
! during the orthonormalization procedure (see below).
! loto_2d : set to .true. to activate two-dimensional treatment of LO-TO splitting.
!
! If a file "fildyn"0 is not found, the code will ignore variable "fildyn"
! and will try to read from the following cards the missing information
! on the q-point grid and file names:
! nr1,nr2,nr3: dimensions of the FFT grid formed by the q-point grid
! nfile : number of files containing C(q_n), n=1,nfile
! followed by nfile cards:
! filin : name of file containing C(q_n)
! The name and order of files is not important as long as q=0 is the first
!
USE kinds, ONLY : DP
USE mp, ONLY : mp_bcast
USE mp_world, ONLY : world_comm
USE mp_global, ONLY : mp_startup, mp_global_end
USE io_global, ONLY : ionode_id, ionode, stdout
USE environment, ONLY : environment_start, environment_end
!
IMPLICIT NONE
!
CHARACTER(len=256) :: fildyn, filin, flfrc, prefix
CHARACTER (LEN=10) :: zasr
LOGICAL :: la2F, loto_2d
INTEGER :: ios
!
NAMELIST / input / fildyn, flfrc, prefix, zasr, la2F, loto_2d
!
CALL mp_startup()
CALL environment_start('Q2R')
!
IF (ionode) CALL input_from_file ( )
!
fildyn = ' '
flfrc = ' '
prefix = ' '
loto_2d=.false.
zasr = 'no'
!
la2F=.false.
!
!
IF (ionode) READ ( 5, input, IOSTAT =ios )
CALL mp_bcast(ios, ionode_id, world_comm)
CALL errore('q2r','error reading input namelist', abs(ios))
CALL mp_bcast(fildyn, ionode_id, world_comm)
CALL mp_bcast(flfrc, ionode_id, world_comm)
CALL mp_bcast(prefix, ionode_id, world_comm)
CALL mp_bcast(zasr, ionode_id, world_comm)
CALL mp_bcast(loto_2d, ionode_id, world_comm)
CALL mp_bcast(la2F, ionode_id, world_comm)
!
CALL do_q2r(fildyn, flfrc, prefix, zasr, la2F, loto_2d)
!
CALL environment_end('Q2R')
CALL mp_global_end()
!
END PROGRAM q2r
!
!----------------------------------------------------------------------------