Second-Order Raman Spectra of Fluorites. II. Lattice Dynamical Analysis

Abstract
The second-order Raman spectra of CaF2, SrF2, BaF2, and PbF2, reported in an earlier publication, have been correlated to two-phonon density of states distributions calculated on the basis of the shell model of Woods et al. In the case of SrF2 and PbF2 the pertinent model parameters were first calculated from existing optical and elastic data for these crystals, while for CaF2 and BaF2 existing parameters, as determined by inelastic neutron scattering, were used.The calculated density of states distributions showed a general agreement with the observed spectral profiles, but agreement in detail was not precise, indicating a need to use more complicated anharmonic lattice models and to adjust the values of the model parameters.