Dear Sonu Kumar What you said is reasonable;) I have two little questions. One: Does LO-TO splitting must disappear at the boundary of Brillouin zone?
Two: I can understand the LO-TO splitting near Gamma point. However, at Gamma point(not near Gamma point), q=0. When q is zero, there is no longitude and transverse mode. Why are there LO-TO splitting at Gamma point? Thanks:) On Fri, Apr 29, 2011 at 1:21 PM, sonu kumar <1009ukumar at gmail.com> wrote: > Dear All QE users, > > i am sorry again, as i havn't corrected the subject title. > > > (2) only cubic crystals has LO and TO braches. >> > > crystals ( having considerable values of macroscopic dielectric constant [ > i suppose > epsilon infinity] and born effective charges, as pointed out by Prof. > Eyvaz Isaev) with low symmetry can, also, have LO-TO splitting. But this can > be different in different symmetry directions, so one has to search all > symmetry directions for this splitting. > > For cubic crystals splitting is equal in all directions. > > with regards, > > -- > Sonu Kumar > > Phd Student > Physics Department > Indian Institute of Technology > Delhi-110016, India > web:-http://www.iitd.ac.in/ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- ____________________________________ Hui Wang School of physics, Fudan University, Shanghai, China -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110429/37e70259/attachment.htm
