[Pw_forum] Three questions about phonon calculation

[xirainbow]

Dear Yu Han Ho:

2011/6/1 yhho <yhho at pub.iams.sinica.edu.tw>

>  Dear all,
> I have some questions about Phonon calculation.
>
> 1. If I use ph.x to run the graphene phonon dispersion and pdos,
>     should I use the q points which is multiple of 6 because of the
> hexagonal shape of grathpene crystal?
>
I do not think so. But before calculation, you must know which q points you
want to get.


>
> 2. When I run phonon-dispersion calculation, it always cost very long cpu
> time. Is that normal?
>
Phonon calculation always costs more time than electron scf calculation.
Approximately, each q point needs 3*n scf calculation(n is the number of
atoms in primitive unit cell).


>
> 3. Can QE calculate vibration mode?
>
Yes , of course.

>     How could I set terms in ph.in to get vibration mode?
>
Searching in google.

>     And how could I plot the vibration mode from the output file?
>
I do not think you can plot it with QE.


>
> Thanks a lot.
>
> best regards,
> Yu Han Ho
>
>
>
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>


-- 
____________________________________
Hui Wang
School of physics, Fudan University, Shanghai, China
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