Dear Mayank! There is no need to use this much high cutoff. First of all see proper convergence with k-points grids. Then "conv_thr" should be less than 10^-12. Before doing phonon calculation do vc-relax with high accuracy. And if you get very small negative value then you can ignore it..
On Wed, May 11, 2011 at 3:18 PM, mayank gupta <mayankaditya at gmail.com>wrote: > Hi Dear User's > > > I am trying to calculate the phonon frequency of SrFeO compund, but I > got negative frequancies at gamma also at other Q points, while I have > chossen very high cutoff (ecut=100Ry and ecut_rho=1000), while > experimentally the structure is stable at room temperature even up to > very low temperature. what could be the possible reason for such > negative frequecies. > > -- > Mayank > > BHABHA ATOMIC RESEARCH CENTER > MUMBAI > Office: 022-25595606 > Home: 9920397437/9869834437 > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Regards, MOHNISH, ----------------------------------------------------------------- Mohnish Pandey Y6927262,5th Year dual degree student, Department of Chemical Engineering, IIT KANPUR, UP, INDIA ----------------------------------------------------------------- -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110512/592fd3f4/attachment.htm
