Dear Ghosh, If I've read the paper correctly, the paper you are looking at is entirely computational, not experimental, so basically you are trying to decide if pseudopotentials used in that paper and in your calculation are going to give the same result. You're not comparing with experiment, which, as has been pointed out by others, is at a high temperature. You want to compare your calculations to Ho's.
So have you tried to duplicate the frozen phonon calculations described in the paper? Or, possibly better, Figure 3? On 05/21/2010 05:41 AM, partha sarathi ghosh wrote: > Dear all, > Thank you xirainbow and Michael J. Mehlfor > for your reply & suggestion . > I was trying to calculate longitudinal phonon dispersion of Zr along > [111] direction. > I wanted to validate my calculation with experimental results for bcc-Zr > (not hcp) given in the paper :Phy.Rev.B,vol-29,page 1575-1587(1984). > But I am getting negative frequencies near q=2/3(1 1 1) and the over all > appearance of the curve is different from the experimental one. I > optimized the system w.r.t ecutwf, ecutrho , k-point sampling , volume > ,degauss, conv_thr. I have also tried with different q-point sampling in > ph.in <http://ph.in> file (like 4 4 4, 8 8 8) with tr2_ph=1.0d-12. > My questions are : > 1. Is DFTP suitable for studying particular phonon mode like in Zr ?? > 2. If yes then how to make my calculations efficient ?? > 3. If not then any suggestion of other methods ?? > Any one can please help me. > Thanks in advance. > P. S. Ghosh > B.A.R.C. > INDIA > > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- Michael J. Mehl Head, Center for Computational Materials Science Naval Research Laboratory Code 6390 Washington DC
