by searching google "non symmetric born effective charge" I found the following reference to a pw_forum previous entry http://www.democritos.it/pipermail/pw_forum/2006-January/003511.html that may be of interest.
There is also a reference to a paper Cockayne-Burton PRB 62, 3735 (2000) on CaTiO3 that maybe is relevant to your case. stefano On 04/07/2011 09:54 AM, mohaddeseh abbasnejad wrote: > Thanks for your reply. > I am working on one of the orthorhombic structures of TiO2. > and it is the first time I have faced this problem. > > Yours, > M. Abbasnejad > University of Tehran > > > On Thu, Apr 7, 2011 at 12:04 PM, Stefano de Gironcoli<degironc at > sissa.it>wrote: > >> what is your system ? >> born effective charges are not necessarily hermitian although very often >> they are. >> stefano >> >> >> On 04/07/2011 09:28 AM, mohaddeseh abbasnejad wrote: >> >> Dear all, >> >> Trying to calculate the born effective charges of my case, the obtained >> diagonalized principal values of effective charge tensor have imaginary >> part. >> >> The system has been relaxed carefully using Perdew-Zunger ultrasoft >> psuedopotentilas by ecutoff=50 (55) Ry, and performing the BZ integration in >> a 6?6?6 grid with 27 reduced >> number of k points in the irreducible edge of the 1st BZ. >> >> What may cause the problem? >> >> >> Thanks for any comment. >> >> Yours, >> M. Abbasnejad >> University of Tehran >> >> >> >> _______________________________________________ >> Pw_forum mailing listPw_forum at >> pwscf.orghttp://www.democritos.it/mailman/listinfo/pw_forum >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> >> > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110407/9a53e1bc/attachment.htm
