Answer to Question #242595 in Physics for Reena Biswas

Question

The tight binding energy dispersion (E-k) relation for electrons in a one-dimensional array of atoms having lattice constant 'a' and total length 'L' is :

E=E0−β−2γcoska

Where E0,β and γ are constants and k is the wave vector.
The number of phonon branch in graphite, with four atoms in the primitive cell, is?

Answer 1

In graphite, with four atoms in the primitive cell there are 12 different phonon branches.

(please see http://nano-bio.ehu.es/files/articles/Wirtz_SSC_2004_382.pdf)