[Pw_forum] phonon frenquecies convergences

[hichem bouderba]

thank you.

On 1/9/12, Paolo Giannozzi <giannozz at democritos.it> wrote:
> On Mon, 2012-01-09 at 10:11 +0000, hichem bouderba wrote:
>
>> Suppose that one performs a convergence study for just one q-point
>> (say Gamma for example), is it reasonable to expect that results will
>> be reliable for other q-points ?
>
> if you check convergence wrt cutoff, or wrt k-points in insulators,
> I would say it is reliable. Convergence wrt k-points may be very
> tricky in metals, though, due to the presence of Kohn anomalies.
>
>> Does the last line mean :
>> (a) Do not use it with non cubic symmetries.
>> (b) One may use it, but results should be carefully checked for
>> eventual problems. In this case, wath kind of problems one may expect.
>
> no major problems, I think: the DOS close to Gamma may be inaccurate
>
> P.
>
> --
> Paolo Giannozzi, IOM-Democritos and University of Udine, Italy
>
>
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-- 
Mr. Hichem Bouderba
département de physique
Université de Batna
Algérie