EVALUATION OF BRILLOUIN-SCATTERING INTENSITIES FROM RARE-GAS CRYSTALS .2. INTRODUCTION OF SHORT-RANGE CORRECTIONS

Corrections to the dipole-induced-dipole theory coming from both electronic overlaps and dispersion-force effects are introduced into the self-consistent equation for the effective atomic polarizability and applied to the case of rare-gas crystals. We show that the one-phonon expansion for Brillouin-scattered intensities can be rigorously solved, with the difference from a pure dipole-induced-dipole theory that Briilouin intensities now contain three microscopic quantities of the system. In the case of krypton crystals these quantities, which are related to the corrections to elasto-optic coefficients, are estimated by using experimental data. A comparison with theoretical predictions and experimental results is discussed. In the case of neon, argon and xenon available experimental data are not sufficient to estimate the three quantities, so just the rates of the elasto-optic coefficients are discussed. A slight discrepancy might be due to an overestimate of the anisotropic short-range contribution coming from the self-consistent-field calculations. © 1990 Taylor & Francis Ltd.