[Pw_forum] symmetry of phonon modes

Munima Bora Sahariah munima at iitg.ernet.in
Wed Mar 26 09:21:58 CET 2008

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


Dr. Munima B. Sahariah
PI, DST Fast Track Project
IASST, Guwahati
Assam, INDIA

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