DIPOLE-INDUCED DIPOLE LIGHT-SCATTERING IN SUPERCOOLED LIQUIDS NEAR THE LIQUID-GLASS TRANSITION

The integrated intensity produced by the dipole-induced dipole (DID) light scattering mechanism in a Lennard-Jones fluid is investigated for different points of the phase diagram corresponding to the normal and undercooled liquid at zero pressure. The exactly computed intensity is compared to the full Kirkwood superposition approximation (KSA) and its so-called Stephen approximation. The latter gives one or two orders of magnitude too large results, while the former is in much better agreement with the exact computation up to large reduced density values. On the basis of the mode coupling theory of the glass transition, it is argued that, in the vicinity of this transition, in real glass forming isotropic molecular liquids for which DID is the only light scattering mechanism, both a dynamical extension of the KSA and its Stephen approximation should yield dynamical spectra proportional to the real ones.