Hi Alex, Thermodynamical quantities depend strongly on low energy phonons ( mainly the acoustic phonons, or the low energy part of the phonon density of states; the Debye part). And to less extent on the high energy modes.
It also depends on how much precise you want to go in your calculations. The more q-vectors you use in your calculations the better convergence of quantities of interests. I think the best thing to do is to sample for once the phonon density of states using a fine mesh of q-vectors, and then to use it to calculate all your quantities for all temperatures of interests. Kindest Regards, __________________________________ Iyad Al-Qasir, PhD Assistant Professor Department of Nuclear Engineering University of Sharjah Sharjah, UAE On Sat, Dec 14, 2013 at 3:04 AM, Alex Granov <alex.granov at outlook.com>wrote: > Hi > > As I understand from Phonon and QHA examples calculation of entire phonon > dispersion is necessary to calculate and prepare fc file then > Thermodynamic properties like Gibbs energy. I wonder if it is possible to > avoid calculating entire phonon dispersion for a very large system say 160 > atoms to calculate its Gibbs energy or not. I appreciate any help in > advance. > > > ------------------------------------------------- > Alex Granov > ?????????? ??????-??????????? ???????? (MIPT) > Moscow, Russia > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20131214/15731401/attachment.html
