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 soli d neon at different temperatures, for longitudinal and transverse phon on modes. The Lennard-Jones potential is considered. The relevance of the quantum effects on the frequency position of the peak and principa lly on the line-width of the spectral shape is clearly pointed out. Th e spectrum is reconstructed via a continued fraction expansion: the ap proximations introduced using the effective potential quantum molecula r dynamics are discussed.