## phonopy-users

 [Phonopy-users] Phonopy encounters symmetry problem for some supercells From: Tian Lan - 2013-04-24 17:42:36 Attachments: Message as HTML ```Dear all, I am using phonopy to calculate phonons for a cuprite structure. I got some negative frequencies in acoustic modes for 2 by 2 by 2 supercell. In order to check whether it really is an unstable structure, or some numerical fake, I plan to increase the supercell in one dimension to enhance the resolution there (I guess this method should work). Therefore, I generate a 1 by 1 by 10 supercell, phonopy created it well and printed down the correct symmetry, and VASP did the force calculation well, and phonopy got the force_sets, so far so good. However, when I tried to get the dispersion or DOS (I have set DIM= 1 1 10 in the control tab), bunches of lines saying 'Phonopy encounters symmetry problem', followed by "Input forces are not enough to calculate force constants, or something wrong (e.g. crystal structure does not match)." I am confused about this error because I am using phonopy generated structure, cuprite is cubic structure, but I don't think supercell has to be the same in all dimension. I changed to a 2 by 2 by 4 cell, the same problems still exist. Could someone help me out, I am using a 1.1 version. Thanks! Best, Tian -- Lan, Tian Ph.D. Candidate, Department of Applied Physics and Materials Science California Institute of Technology, Caltech M/C 138-78, Pasadena, CA, 91125 ```
 Re: [Phonopy-users] Phonopy encounters symmetry problem for some supercells From: Atsushi Togo - 2013-04-25 00:03:37 ```Hi, Please use the latest version. http://sourceforge.net/projects/phonopy/ Togo On Thu, Apr 25, 2013 at 2:42 AM, Tian Lan wrote: > Dear all, > > I am using phonopy to calculate phonons for a cuprite structure. I got some > negative frequencies in acoustic modes for 2 by 2 by 2 supercell. In order > to check whether it really is an unstable structure, or some numerical fake, > I plan to increase the supercell in one dimension to enhance the resolution > there (I guess this method should work). > > Therefore, I generate a 1 by 1 by 10 supercell, phonopy created it well and > printed down the correct symmetry, and VASP did the force calculation well, > and phonopy got the force_sets, so far so good. However, when I tried to get > the dispersion or DOS (I have set DIM= 1 1 10 in the control tab), bunches > of lines saying 'Phonopy encounters symmetry problem', followed by "Input > forces are not enough to calculate force constants, or something wrong (e.g. > crystal structure does not match)." > > I am confused about this error because I am using phonopy generated > structure, cuprite is cubic structure, but I don't think supercell has to be > the same in all dimension. I changed to a 2 by 2 by 4 cell, the same > problems still exist. > > Could someone help me out, I am using a 1.1 version. > > Thanks! > > Best, > Tian > > -- > Lan, Tian > Ph.D. Candidate, Department of Applied Physics and Materials Science > California Institute of Technology, > Caltech M/C 138-78, Pasadena, CA, 91125 > > ------------------------------------------------------------------------------ > Try New Relic Now & We'll Send You this Cool Shirt > New Relic is the only SaaS-based application performance monitoring service > that delivers powerful full stack analytics. Optimize and monitor your > browser, app, & servers with just a few lines of code. Try New Relic > and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_apr > _______________________________________________ > Phonopy-users mailing list > Phonopy-users@... > https://lists.sourceforge.net/lists/listinfo/phonopy-users > -- Atsushi Togo http://atztogo.github.com/ atz.togo@... ```
 Re: [Phonopy-users] Phonopy encounters symmetry problem for some supercells From: Atsushi Togo - 2013-04-25 02:17:15 ```I forget about older versions after releasing newer one. Togo On Thu, Apr 25, 2013 at 9:39 AM, wrote: > Thanks, so this is a known bug in the old version? > Best, > Tian > >> Hi, >> >> Please use the latest version. >> http://sourceforge.net/projects/phonopy/ >> >> Togo >> >> On Thu, Apr 25, 2013 at 2:42 AM, Tian Lan wrote: >>> Dear all, >>> >>> I am using phonopy to calculate phonons for a cuprite structure. I got >>> some >>> negative frequencies in acoustic modes for 2 by 2 by 2 supercell. In >>> order >>> to check whether it really is an unstable structure, or some numerical >>> fake, >>> I plan to increase the supercell in one dimension to enhance the >>> resolution >>> there (I guess this method should work). >>> >>> Therefore, I generate a 1 by 1 by 10 supercell, phonopy created it well >>> and >>> printed down the correct symmetry, and VASP did the force calculation >>> well, >>> and phonopy got the force_sets, so far so good. However, when I tried to >>> get >>> the dispersion or DOS (I have set DIM= 1 1 10 in the control tab), >>> bunches >>> of lines saying 'Phonopy encounters symmetry problem', followed by >>> "Input >>> forces are not enough to calculate force constants, or something wrong >>> (e.g. >>> crystal structure does not match)." >>> >>> I am confused about this error because I am using phonopy generated >>> structure, cuprite is cubic structure, but I don't think supercell has >>> to be >>> the same in all dimension. I changed to a 2 by 2 by 4 cell, the same >>> problems still exist. >>> >>> Could someone help me out, I am using a 1.1 version. >>> >>> Thanks! >>> >>> Best, >>> Tian >>> >>> -- >>> Lan, Tian >>> Ph.D. Candidate, Department of Applied Physics and Materials Science >>> California Institute of Technology, >>> Caltech M/C 138-78, Pasadena, CA, 91125 >>> >>> ------------------------------------------------------------------------------ >>> Try New Relic Now & We'll Send You this Cool Shirt >>> New Relic is the only SaaS-based application performance monitoring >>> service >>> that delivers powerful full stack analytics. Optimize and monitor your >>> browser, app, & servers with just a few lines of code. Try New Relic >>> and get this awesome Nerd Life shirt! >>> http://p.sf.net/sfu/newrelic_d2d_apr >>> _______________________________________________ >>> Phonopy-users mailing list >>> Phonopy-users@... >>> https://lists.sourceforge.net/lists/listinfo/phonopy-users >>> >> >> >> >> -- >> Atsushi Togo >> http://atztogo.github.com/ >> atz.togo@... >> > > -- Atsushi Togo http://atztogo.github.com/ atz.togo@... ```