[QE-users] Issue with highest frequency optical band phonons at gamma point in GaN

[Baer, Bradly]

Nicola,

The image is in the outputs folder as "gan.phonons.bands.ps" That is the native output from the plotbands.x code as far as I know.  It is possible that it has been slow to finish uploading from my computer to the google drive though.

I will take a look at the links you provided and I appreciate you taking the time to write your reply.

Thanks,
Brad

--------------------------------------------------------
Bradly Baer
Graduate Research Assistant, Walker Lab
Interdisciplinary Materials Science
Vanderbilt University


________________________________
From: Nicola Marzari <nicola.marzari at epfl.ch>
Sent: Tuesday, March 24, 2020 5:36 PM
To: Quantum ESPRESSO users Forum <users at lists.quantum-espresso.org>; Baer, Bradly <bradly.b.baer at Vanderbilt.Edu>
Subject: Re: [QE-users] Issue with highest frequency optical band phonons at gamma point in GaN



Dear Bradly,

without seeing the image (wasn't there in the google folder) the obvious
guess is that phonons in polar materials require a special treatment -
maybe have a look at
https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjournals.aps.org%2Fprb%2Fabstract%2F10.1103%2FPhysRevB.43.7231&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7Cf6d82383087c4065e82a08d7d043c71f%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C0%7C637206861856438833&sdata=Gj4zzJGY%2F4QRFV6oBN83EmExNE%2F4LNuH3O7RgByRyFA%3D&reserved=0 or
https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fjournals.aps.org%2Frmp%2Fabstract%2F10.1103%2FRevModPhys.73.515&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7Cf6d82383087c4065e82a08d7d043c71f%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C0%7C637206861856438833&sdata=neMQPei1nhq7HnGSESWkLMzfvGC6bJ2XZP3l3U9Qtig%3D&reserved=0

A summary by Paolo Giannozzi on using PHonon is here:
https://nam04.safelinks.protection.outlook.com/?url=http:%2F%2Fwww.fisica.uniud.it%2F~giannozz%2FQE-Tutorial%2F&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7Cf6d82383087c4065e82a08d7d043c71f%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C0%7C637206861856448828&sdata=BMa2Mv%2Fr2wT9iCutYqRRcMugfMEBkvJTUAj9LKjXOxw%3D&reserved=0

                        nicola



On 24/03/2020 23:27, Baer, Bradly wrote:
> Hello everyone,
>
> I am attempting to generate the phonon dispersion plot for ZincBlende
> GaN.  The highest frequency optical band of the dispersion is producing
> the wrong result at the gamma point.  The rest of the dispersion looks
> correct for the most part.  Below is a link to a google drive folder
> with a copy of my current input and output files.  It also has an image
> of the dispersion as plotted by plotbands.x.  I also tried the same
> calculation in SiC and saw the same issue at the gamma point (both are
> FCC).  Am I doing something incorrectly that would cause an issue at the
> gamma point only?  I appreciate any advice on the matter.
>
> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Fopen%3Fid%3D13WDzUBL3DNwasxsDR1gz47MIDh8LtMLZ&data=02%7C01%7Cbradly.b.baer%40vanderbilt.edu%7Cf6d82383087c4065e82a08d7d043c71f%7Cba5a7f39e3be4ab3b45067fa80faecad%7C0%7C0%7C637206861856448828&sdata=%2BhHaIluljELkLOzsNDmP%2F2YfhboZrcCUGdBv7XhrCPc%3D&reserved=0
>
> Thanks,
> Brad
>
> --------------------------------------------------------
> Bradly Baer
> Graduate Research Assistant, Walker Lab
> Interdisciplinary Materials Science
> Vanderbilt University
>
>
>
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--
----------------------------------------------------------------------
Prof Nicola Marzari, Chair of Theory and Simulation of Materials, EPFL
Director, National Centre for Competence in Research NCCR MARVEL, EPFL
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