Molecular dynamics study of Rayleigh light scattering from molecular fluids

Abstract

In this article, we present the results of a molecular dynamics simulation of Rayleigh light scattering (LS) from molecular fluids. We include the orientational and collision induced (CI) contributions to the depolarized LS time correlation and the CI contribution to the isotropic LS time correlation. The intermolecular potential is represented by a two site Lennard-Jones model. The bond length and potential parameters are chosen to correspond to those of O2 and CO2. We consider two pair polarizability models, one based on the dipole-induced dipole (DID) interactions between molecular centers and the other on the DID interactions between Lennard-Jones sites. For both models, we study the variations of the LS time correlations, integrated intensities, and spectral moments with density and temperature. In the case of the more anisotropic CO2, we find that the two models predict very different behavior of the CI part of the Rayleigh LS spectra. The site DID model is found to agree slightly better with the available experimental data. We discuss the implications of our results to the interpretation of Rayleigh spectra in terms of structure and dynamics of molecular fluids.