[Pw_forum] Phonon DOS per polarization

[Lorenzo Paulatto]

Dear Bo,
as long as you can properly characterize the band, it is not hard to do:
you can use matdyn.x to compute the phonon in a dense grid of q-points, you
can generate it with pw.x or with the kpoint.x utility. Then load the grid
in matlab or octave or similar and integrate it properly. Since some time
ago, the matdyn code produce a *.gp code which is very practical for this
kind of analysis.

The problem is deciding which is band X, as soon as they start to cross
deciding which is which is not trivial. There is an option in matdyn to
assign the phonon bands order using eigenvectors continuity. However, this
method works well for high-symmetry lines, but may be not so robust when
doing a 3D grid of points. Yet, it is worth trying.

Provided all these difficulties, in many case and as long as you are
interested in a phonon band that is well separated from  the others there
may be no problem at all. Finally, you can think of a specific criteria to
discriminate the bands in a specific material, but implementing it is up to
you.

bests

-- 
Dr. Lorenzo Paulatto
IdR @ IMPMC -- CNRS & Université Paris 6
phone: +33 (0)1 44275 084 / skype: paulatz
www:   http://www-int.impmc.upmc.fr/~paulatto/
mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
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