The mechanisms of light scattering in deeply supercooled ${\mathrm{CS}}_2$ have been studied using instantaneous normal modes. Changes in the many-body polarizability due to orientational fluctuations are found to be the predominant scattering mechanism, while density fluctuations play only a minor role. Although the density and orientational fluctuations are found to be highly coupled, the light-scattering susceptibility does not closely resemble the intrinsic spectrum of density fluctuations. These results suggest that light-scattering data do not provide a reliable probe of density fluctuations in molecular liquids.

• Received 23 April 1999

DOI:https://doi.org/10.1103/PhysRevLett.83.3550