[Pw_forum] quick question about the input file for phonon calculations at a point
Stefano de Gironcoli
degironc at sissa.it
Wed May 9 21:56:43 CEST 2012
qx, qy, qz are in unit of 2pi/alat
which means that, for instance, in a simple cubic lattice the zone
boundary along x has coordinates (0.5,0.0,0.0) because b1=(1,0,0)*2pi/a
in an fcc lattice the zone boundary in the x direction is instead
(1,0,0) because in fcc the smallest G vector in that direction is
(2,0,0)*2pi/a
stefano
On 05/09/2012 09:38 PM, Elie M wrote:
> Dear all, I have a simple question about the coordinates of the point at which one would like to perform phonon calculations. It is just a quick check really. I am talking about the following input file for example:
> Phonon
> dispersion for monolayer grapheme at the gamma point
>
> &inputph
>
> tr2_ph=1.0d-14,
>
> prefix='phmonog',
>
> trans=.true.,
>
>
> recover=.true.,
>
> amass(1)=12.0107,
>
> outdir='/tmp/',
>
> fildyn='mgraph.dynG',
>
> /
>
> qx qy qz<------The point at which the phonon calculation is run.
> In what coordinate system must (qx,qy,qz) be expressed? Is it written in units of 2Pi/alat? and if so, should alat be in Angstroms or a.u.?
> Thanks
> Elie Moujhes
> University of NottinghamNG7 2RDUK
>
>
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