[Pw_forum] Can I use resluts of gamma point to calculate the phonon dispersion curve?

stefano de gironcoli degironc at sissa.it
Tue Sep 24 13:27:30 CEST 2013

in order to generate interatomic force constants that then give you 
phonon dispersions you need to compute dynamical matrices for a grid of 
q points (1d grid in your case i would say). gamma is a point always 
present in the grid so you can reuse its data.
how many additional points you need to add depends on how far the 
interatomic force constants extend and how large is your system.
for large systems even just gamma might be enough (need to be tested)

On 09/24/2013 03:19 AM, Peng Tao wrote:
> Dear all,
> I have calculated the phonon frequencies of gamma point before, and now I'm planning to
> calculate its phonon dispersion curve. Can I use the results of gamma point? If not, phonon
> of the gamma point needs to be recalculated, which is really a waste of time.
> My system is quite large and one-dimensional, so the gamma point is exclusively important.
> If it is possible to make use of previous results, plenty of time will be saved.
> Thank you very much!
> Warmest regards,
> Peng Tao
> --
> -------------------------------------------------------------------
> PH.D. candidate Peng Tao
> Magnetism and Magnetic Materials Division
> National Laboratory for Material Science
> Institute of Metal Research, Chinese Academy of Sciences
> Phone  +86-024-83978751
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