close to gamma the acoustic branches have linear dispersion. Away from gamma one should follow the modes that are connected to these three modes at gamma. If there is no symmetry these are just the three lowest branches. If there is some symmetry they can cross a few branches with different symmetry labels and should be possible to follow the acoustic ones comparing the eigenvectors. But I dont see any special meaning of acoustic modes far away from gamma. What are you looking for ?
stefano meheut at impmc.jussieu.fr wrote: > Dear Drs, > > I would like to use pwscf to compute the acoustic branches only of the > crystal. I already computed the complete phonon dispersion, but the > acoustic branches are crossing with other modes. Do you think possible > to disjoin the acoustic modes frequencies from the other modes? > > Best wishes. > > Merlin meheut > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum
