The dispersion relation of phonons in solid is given by o(k) = o(3- cos ka- cos ka -cos ka the velocity of the phonons at large wavelength is 25. (a) (b) oa v3

The dispersion relation of phonons in solid is given by o(k) = o(3- cos ka- cos ka -cos ka The velocity of the phonons at large wavelength is 25. (A) (B) oa V3 (C) v30,a (D)