[Pw_forum] Conservation of projected phonon DOS

[Eyvaz Isaev]

Dear Chen,

Can you please send me your FC files, so that I can play around?

Bests,
Eyvaz.
-------------------------------------------------------------------
Prof. Eyvaz Isaev, 
Department of Physics, Chemistry, and Biology (IFM), Linkoping University, 
Sweden 

Theoretical Physics Department, Moscow State Institute of Steel & Alloys, 
Russia, 

isaev at ifm.liu.se, eyvaz_isaev at yahoo.com




________________________________
From: Chen Li <lichen at caltech.edu>
To: pw_forum at pwscf.org
Sent: Fri, January 7, 2011 8:34:31 PM
Subject: [Pw_forum] Conservation of projected phonon DOS

Dear All,

I'm wondering if anyone else had encountered similar problem before. Any 
suggestions will be greatly appreciated.

I have been using the QHA code and our own code to calculated the atomic 
projected phonon DOS using the phonon eigenvectors from QE phonon calculation. 
Both methods gave very similar results, so I have no doubt about that part. 

For two different structures, ScF3 (cubic) and ZrO2 (monoclinic), the projected 
phonon DOS didn't have the correct ratio between species. For example, one will 
expect that oxygen will have twice as much contribution as from Zr in ZrO2, but 
the actual ratio is about 1.4 instead. Each atom in unit cell is supposed to 
have 3 degrees of freedom but Zr ended up with 3.7 while oxygen is about 2.6. 
(It is strange that the total degrees of freedom still add up to 9, as 
expected. 

I has used the our code on the eigenvectors from VASP calculation and it gives 
the correct ratio. (I even adapted the VASP eigenvector format to be used with 
QHA code. The results are good too.) It seems the eigenvectors from QE may have 
some problem or maybe there is some factors to them? I'm pretty confident about 
the convergence of the calculations. It is also unlikely the convergence of 
calculation will give that much difference because it should not change the 
phonon DOS conservation anyway.

Regards,
Chen Li
Materials Science
California Institute of Technology
MC 138-78 1200 E California Blvd
Pasadena, CA 91125



      
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