[Pw_forum] phonon branch sorting

Derek Stewart stewart at cnf.cornell.edu
Fri Oct 26 16:23:09 CEST 2012

Dear Bo and Lorenzo,

I have one more suggestion on the issue of phonon branch sorting. I ran 
into this problem a while back, while working on a project on thermal 
transport in indium arsenide nanowires.  I ended up using an sorting 
algorithm that Keith Refson developed for use with phonon calculations 
in the CASTEP code.  This script works by calculating overlap matrices 
between eigenvectors at neighboring q-points.  Keith recently licensed 
this script as GPL and I have written a tool to convert the matdyn 
phonon output to the CASTEP phonon format.  For my project, I found that 
as long as you have a fairly dense mesh of q-points, it worked very well.

I am planning to put these scripts up on the web soon once I have a 
short example run to go with it.  I'll send a note to the PWSCF forum 
when it is ready.  Bo, in the meantime, I would be happy to send you the 
scripts if you are interested.

Best regards,


Derek Stewart, Ph. D.
Senior Research Associate
250 Duffield Hall
Cornell Nanoscale Facility (CNF)
Ithaca, NY 14853
stewart (at) cnf.cornell.edu
(607) 255-2856

On 10/26/2012 8:00 AM, Lorenzo Paulatto wrote:
> On 26 October 2012 07:55, Bo Qiu <200210qb at gmail.com 
> <mailto:200210qb at gmail.com>> wrote:
>     Dear Dr. Paulatto,
>     Thanks a lot for the explanations! I'm actually writing a small
>     code to order phonon bands based on eigenvector continuities on a
>     3d grid. Thanks for pointing out there is already such option in
>     matdyn.x, I'll definitely check it out. I have finished a
>     preliminary test for my code on Al for a band crossing along
>     Gamma-K direction -- it seems to be well captured, but band
>     orderings are wrong at some random point where there is actually
>     no band crossing. I'll try to figure it out and also referring to
>     the matdyn.f90 to see what else I can do.
>     On the other hand, I think for electronic band structures one will
>     have the same problem with band ordering -- though most of time
>     people are only interested about those very few bands near Fermi
>     level. I wonder in the case of electronic band structure whether
>     continuity of wavefunction should be used to deal with band
>     ordering with band crossing? Thanks a lot!
> The bands.x code already does that, i.e. it sorts the bands using the 
> overlap of wavefunctions at consequent k-points. Again, this is an 
> option that works well for line plots, but I'm not sure it always make 
> sense to use in a 3D dispersion. Or at least, it would need to be 
> modified to sort according to neighboring points, not just according 
> to the previous point in the input list. It is not very hard to do, 
> but a bit boring as it requires a rethinking of the code structures.
> 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/ 
> <http://www-int.impmc.upmc.fr/%7Epaulatto/>
> mail:  23-24/4é16 Boîte courrier 115, 4 place Jussieu 75252 Paris Cédex 05
> _______________________________________________
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