Is the frequency on the phonon. Making the approximation that the frequency is inversely proportional to your wavelength, It was extended imagined that phonon theory is not able to describe the heat capacity of liquids, since liquids only sustain longitudinal, although not transverse phonons, which in solids are responsible for https://www.quora.com/profile/Trevor-Flatcher-2/Silicon-carbide-special-ceramics-in-modern-industry-in-a-variety-of-applications-Silicon-Carbide-Special-Ceramics-in-Mo