The mechanisms of light scattering in deeply supercooled CS2 have been stud
ied using instantaneous normal modes. Changes in the many-body polarizabili
ty due to orientational fluctuations are found to be the predominant scatte
ring 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 intrinsi
c spectrum of density fluctuations. These results suggest that light-scatte
ring data do not provide a reliable probe of density fluctuations in molecu
lar liquids.