# Input File Description ## Program: q2r.x / PHonon / Quantum ESPRESSO (version: 6.7GPU)
> > ### TABLE OF CONTENTS INTRODUCTION &INPUT fildyn | flfrc | zasr | loto_2d Line-of-input: nr1 | nr2 | nr3 fileSpecs nfile | file ### INTRODUCTION
> >     Purpose of q2r.x:

> >     It reads force constant matrices C(q) produced by the ph.x code
> >     for a grid of q-points and calculates the corresponding set
> >     of interatomic force constants (IFC), C(R)

> >     Input data format: [ ] = it depends

> >     Structure of the input data:
> >     ========================================================================

> >     &INPUT
> >        ...specs of namelist variables...
> >     /

> >     [ nr1 nr2 nr3
> >       nfile
> >          file(1)
> >          file(2)
> >          ...
> >          file(nfile) ]
## Namelist: &INPUT
fildyn | CHARACTER
Status: | REQUIRED
>     Input file name (must be specified).

>     "fildyn"0 contains information on the q-point grid

>     "fildyn"1-N contain force constants C_n = C(q_n),
>          where 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.
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flfrc | CHARACTER
Status: | REQUIRED
>     Output file containing the IFC in real space (must be specified)
[Back to Top]
zasr | CHARACTER
Default: | 'no'
>     Indicates the type of Acoustic Sum Rules used for the Born
>     effective charges.

>     Allowed values:
>   `'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).
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loto_2d | LOGICAL
>     set to .true. to activate two-dimensional treatment
>     of LO-TO splitting.
[Back to Top]
> IF `file {fildyn}0 does not exist :`
>     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:
> ### Line of input
> ### Syntax: nr1 nr2 nr3
> > ### Description of items:
> > nr1, nr2, nr3 | INTEGER
> > >     dimensions of the FFT grid formed by the q-point grid
> [Back to Top]
> ## Card: fileSpecs
> > ### Syntax: nfile
> > file(1)
> > file(2)
> > . . .
> > file(nfile)
> > ### Description of items:
> > nfile | INTEGER
> > >     number of files containing C(q_n), n=1,nfile
> > [Back to Top]
> > file | CHARACTER
> > >     names of the files containing C(q_n), n=1,nfile

> > >     Note that the name and order of files is not important as
> > >     long as q=0 is the first.
> [Back to Top]

This file has been created by helpdoc utility on Thu Apr 22 16:16:57 CEST 2021.