Hi Ezad, There's an example in Ashcroft's and Mermin's "Solid State Physics" (Ch. 22, p 433 in my copy) in which they take the parametres of a linear chain with a basis so that it's equivalent to solving the monoatomic linear chain. What you see in this case is similar to "folding" the phonon branch.
Doing something similar for the bandstructure would also result in folding, since there is no bragg reflection to split the bands near the "zone boundary". I suppose one sees the same behaviour on "SC Si", but one should have to be very careful to select the same (or equivalent) q points (due to the different basis you're using). I hope this gives some hints. Regards, Miguel Ezad Shojaee escribi?: > Hi > It seems that if we look to Si lattice as an SC with 8 atoms per cell, > the symmetries connected to the fractional translations will not be > accepted, so if we use this scheme to obtain the zone-center phonons of > Si, we will get frequencies rather different from the main one(FCC > scheme), with different symmetries and degenerecies. > How is it possible to obtain the right ones (zone-center phonons) of Si, > with the right symmetries and degenerecies, by the SC scheme? > Thanx > > ------------------------------------------------------------------------ > Connect to the next generation of MSN Messenger Get it now! > <http://imagine-msn.com/messenger/launch80/default.aspx?locale=en-us&source=wlmailtagline> > > > ------------------------------------------------------------------------ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -- ---------------------------------------- Miguel Mart?nez Canales Dto. F?sica de la Materia Condensada UPV/EHU Facultad de Ciencia y Tecnolog?a Apdo. 644 48080 Bilbao (Spain) Fax: +34 94 601 3500 Tlf: +34 94 601 5326 ---------------------------------------- "If you have an apple and I have an apple and we exchange these apples then you and I will still each have one apple. But if you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas." George Bernard Shaw
