Question

Consider a square lattice that has got one atom of mass m at one lattice point. It interacts with 1 st nearest neighbours only and phonon dispersion relation varies sinusoidally. (a) In the long-wavelength limit, obtain the density of phonon states D(ω) = dN/dω, i.e., the number of lattice-vibration modes per frequency. (10) (b) At high temperature (kT >> ħω), find the mean square displacement of an atom from its equilibrium position, and comment on the stability of two- dimensional crystals interval dω. (10)

Answer 1

Answer:

"dN" (and any subsequent words) was ignored because we limit queries to 32 words.