[Pw_forum] sorting phonon bands based on symmetry/eigenvectors

[Derek Stewart]

Dear Stefano,

Thank you very much for the suggestion.  I'll see what I can find 
regarding the vibrational Wannier functions and I will be glad to report 
back if I come across some interesting options.

Regards,

Derek

################################
Derek Stewart, Ph. D.
Scientific Computation Associate
** New Webpage **
http://sites.google.com/site/dft4nano/
250 Duffield Hall
Cornell Nanoscale Facility (CNF)
Ithaca, NY 14853
stewart (at) cnf.cornell.edu
(607) 255-2856




Stefano Baroni wrote:
> Derek: I do not think/know that/if anything is implemented already, 
> but you problem was elegantly addressed some time ago by Karin Rabe 
> who introduced the concept of "vibrational Wannier function" (or 
> something like that). You may want to browse the literature and report 
> to us if you find anything meaningful/interesting. I maintain, though, 
> that the process you want to automate can be automated using IFC as 
> well. Cheers - Stefano
>
> On Dec 8, 2009, at 4:07 PM, Derek Stewart wrote:
>
>> Hi Miguel,
>>
>> Thank you for your quick response and advice.  I agree that with the
>> cheap cost of calculating phonon points once you have the IFC, a visual
>> inspection of the plot is usually enough to order the phonon dispersion
>> along a given symmetry line in the Brillouin Zone.
>>
>> However, I would like to be able to sort the phonon frequencies for a
>> large number of q-vectors in the Brillouin zone (not just restricted to
>> a single symmetry line) and for this it would be very helpful if I can
>> automate the process.
>>
>> I know that for electronic bands, it is possible to determine the
>> symmetry character of a given electronic band using sym_band.f90.  Would
>> it be possible to use the same subroutines to determine the symmetry
>> character of the phonon bands?  I could then sort based on this output.  
>> If anyone has some thoughts on this, I would be very interested.
>>
>> Thanks,
>>
>> Derek
>>
>> ################################
>> Derek Stewart, Ph. D.
>> Scientific Computation Associate
>> ** New Webpage **
>> http://sites.google.com/site/dft4nano/
>> 250 Duffield Hall
>> Cornell Nanoscale Facility (CNF)
>> Ithaca, NY 14853
>> stewart (at) cnf.cornell.edu
>> (607) 255-2856
>>
>>
>>
>>
>> Miguel Martínez wrote:
>>> Dear Derek,
>>>
>>> I recently discovered that plotband.x is also able to plot phonon bands
>>> as well as band structures. Just set all the references to 0. In any
>>> case, if you have the IFC you shouldn't have issues distinguishing
>>> crossing from anticrossing. Adding more points to the dispersion bands
>>> is almost free, after all. At least it is in the smallish systems I've
>>> done phonon calculations for.
>>>
>>> Regards,
>>>
>>> Miguel
>>>
>>> On Mon, 07 Dec 2009 13:42:50 -0500 Derek Stewart
>>> <stewart at cnf.cornell.edu> wrote:
>>>
>>>> Hi everyone,
>>>>
>>>> I was wondering if anyone has written a script or program to sort the
>>>> phonon frequencies based on their band index or branch.  This would
>>>> be very helpful for both plotting and post-analysis.  Currently when
>>>> you use matdyn for a given set of q-vectors, it prints out the phonon
>>>> frequencies in order from lowest to highest.  However, this does not
>>>> take into account the possibility of band crossings which can lead to
>>>> changes in the order of the bands.  Matdyn also prints out the
>>>> eigenvectors for the phonons so it should be possible to analyze this
>>>> and then sort them.   If someone has already addressed this issue, I
>>>> would be very interested in any tools that can handle this.
>>>>
>>>> Thanks,
>>>>
>>>> Derek
>>>>
>>>> ################################
>>>> Derek Stewart, Ph. D.
>>>> Senior Research Associate
>>>> ** New Webpage **
>>>> http://sites.google.com/site/dft4nano/
>>>> 250 Duffield Hall
>>>> Cornell Nanoscale Facility (CNF)
>>>> Ithaca, NY 14853
>>>> stewart (at) cnf.cornell.edu
>>>> (607) 255-2856
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>>
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>
> ---
> Stefano Baroni - SISSA  &  DEMOCRITOS National Simulation Center - Trieste
> http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / 
> stefanobaroni (skype)
>
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