Debye model in Statistical Physics

[M. next]

Was Debye's basic idea for a solid body to neglect the dispersion Einstein talked about in his model?

 

[Jano L.]

What model do you mean? The Einstein model of specific heat of solid? If so, then it was quite the opposite way: the Einstein model considers atoms as independent oscillators of the same frequency. The Debye model, on the other hand, considers normal modes of the whole solid body, and thus includes dispersion - different modes have different frequencies.

 

[M. next]

At k< π/a (a being interatomic distance, dispersion didn't exist in Einstein's model, but at k>π/a dispersion exists). Correct me if am wrong.