[Pw_forum] why K-X point of phonon dispersion is wrong?

Eyvaz Isaev eyvaz_isaev at yahoo.com
Fri May 6 13:51:26 CEST 2011


First of all I would recommend  the use of PlotPhon utility to plot phonon 
dispersion relations. For this one you have to have calculated interatomic force 
constants matrix (*.fc) file.

Regarding your particular question: you should choose K(0.75,0.75,0), then from 
the  K point go to the X point (1, 1, 0) which is equivalent to 

the X(1,0,0) point. Then from the X(1,0,0) to the Gamma (0,0,0) point.
Dashed line just means that we can continue in this direction to match phonons 
at the X point (i.e. it is an intermediate point from the Gamma to the X point) 

Please also provide your affiliation.


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

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

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

From: lucking-pine <songsong19840614 at gmail.com>
To: Pw_forum at pwscf.org
Sent: Fri, May 6, 2011 2:50:16 PM
Subject: [Pw_forum] why K-X point of phonon dispersion is wrong?

My pwscf is used in calculating Si phonon dispersion.The trend of picture in 
most special Symmetry is right.But the only K-X is wrong.I use Xcrysden to 
get K-point.
I found most paper is dash line in 'K' point.So what is mean? Please anyone 
could tell me!  Thanks!
The attachment is my picture and reference paper.
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