Abstract
The polarizability α and quadrupole moment Θ matrix elements for librational excitation of a molecule in a crystal and their thermal averages are given in the harmonic Einstein approximation. The averaging over zero point motion results in a larger reduction of Θ and of the anisotroipic part of the polarizability γ for two librations of a linear molecule and hence, the relative intensity of anisotropic Raman lines.