Temperature Dependence of Molecular Motions in Naphthalene and Anthracene Crystals

Abstract As some of their lattice properties are estimated in the harmonic approximation, the amplitudes of the molecular motions for naphthalene and anthracene crystals have been calculated. Comparison between the results obtained either by a full dynamical calculation (i.e. tensors L and T) or by the simplified Cruickshank's theory with the values deduced from X-ray experiments is presented. In addition, the temperature dependence of molecular motions in naphthalene crystal is given in a wide range (from 77 K up to sublimation temperature).