> Dear all, > Dear Yu Han Ho
> I have some questions about Phonon calculation. > > 1. If I use ph.x to run the graphene phonon dispersion and pdos, > should I use the q points which is multiple of 6 because of the > hexagonal shape of grathpene crystal? > It need not be multiples of 6.....what you should keep in mind is that you should odd q-point unshifted grid (i.e. 3x3 or 5x5 or 6x6) so that you retain the symmetry of the unit cell. > 2. When I run phonon-dispersion calculation, it always cost very long cpu > time. Is that normal? > It is expensive......for each mode the calculation time is of the order of one scf cycle. > > 3. Can QE calculate vibration mode? > How could I set terms in ph.in to get vibration mode? > The eigenvectors corresponding to each eigen value represent the vibrational modes. In order to find out how to set up the input files please refer to the examples. > > And how could I plot the vibration mode from the output file? > > I do not know whether there is some direct post processing utility available to do that.....however, you can use xcrysden to plot the modes......in order to know how to do it you can refer to the following link: http://www.xcrysden.org/doc/vectorField.html In place of Fx, Fy and Fz, you need to put in the eigen vectors. > Thanks a lot. > > > You are welcome. Also please remember to provide your affiliation. Prasenjit -- PRASENJIT GHOSH, Assistant Professor, IISER Pune, First floor, Central Tower, Sai Trinity Building Garware Circle, Sutarwadi, Pashan Pune, Maharashtra 411021, India Phone: +91 (20) 2590 8203 Fax: +91 (20) 2589 9790 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110601/d6bafb84/attachment.htm