The frequency ω(λ) of the vibrational mode of wave length λ is altered if the crystal is mechanically compressed. To describe this effect Gruneisen introduced the ``Gruneisen parameter''
γ≡−ω(λ)VdVdω(λ)
Taking γ as a constant (independent of λ,V,T,…) calculate the mechanical equation of state P(T,V,N) for a Debye--Gruneisen crystal.
Show that for a Debye--Gruneisen crystal
vα=γkTcv