[Pw_forum] symmetry of phonon modes

Dal Corso Andrea dalcorso at sissa.it
Wed Mar 26 12:19:02 CET 2008

Please check the troubleshooting section of the user guide at the point:

pw.x doesn’t find all the symmetries you expected

Hope this helps.


On Wed, 2008-03-26 at 13:51 +0530, Munima Bora Sahariah wrote:
> Dear PWscf users,
> I am doing some phonon calculations in a wurtzite material having space
> group P6_3 mc (186). Typically, for this structure, we should get 12
> phonon branches grouped into the 2E_2 + 2E_1 + 2A_1 + 2B_1 irreducible
> representation at gamma point. However in my phonon output file, I get 8
> phonon modes which are marked  as A' and rest 4 as A'' which fall into
> some other point groups. I am using espresso-3.2.3.
> Could anyone please explain what is going wrong?  Moreover I would like to
> know how one can determine the symmetry labels of a given phonon mode from
> the pwscf outputs without using the standard symmetry analizer included in
> espresso-3.2 onwards.
> I am new to this pwscf code and to phonon  calculations as well. So I
> would highly appreciate some elaborate suggestion/explanation in this
> matter.
> Thanks
> _____________________________
> Dr. Munima B. Sahariah
> PI, DST Fast Track Project
> IASST, Guwahati
> Assam, INDIA
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Andrea Dal Corso                    Tel. 0039-040-3787428
SISSA, Via Beirut 2/4               Fax. 0039-040-3787528
34014 Trieste (Italy)               e-mail: dalcorso at sissa.it

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