Spectral shapes of solid neon

We present a path integral Monte Carlo calculation of the first three moments of the displacement-displacement correlation functions of solid neon at different temperatures, for longitudinal and transverse phonon modes. The Lennard-Jones potential is considered. The relevance of the quantum effects on the frequency position of the peak and principally on the line-width of the spectral shape is clearly pointed out. The spectrum is reconstructed via a continued fraction expansion: the approximations introduced using the effective potential quantum molecular dynamics are discussed.