On binary collision theories of relaxation in liquids

Abstract

We discuss the properties of many-body correlation functions and spectra in liquids, and the corresponding binary (two-body) approximations. We prove that for a general class of triple collisions the many-body and binary spectra become the same at high frequencies; this is illustrated by an explicit model calculation of force spectra and autocorrelation functions. Applications are made to the study of depolarized scattering and to vibrational relaxation in liquids.