BINARY COLLISION CONTRIBUTION TO THE LONGITUDINAL CURRENT CORRELATION-FUNCTION OF DENSE FLUIDS

An expression for the binary collision contribution to the first-order space-time memory function of the longitudinal current correlation fu nction has been obtained by using the cluster expansion technique for a fluid whose particles are interacting through a continuous potential . This expression involves the radial distribution function and time d ependence of the position, momentum, and acceleration vectors of the p articles. The long-wavelength limit of the expression is obtained for use in studying the longitudinal and bulk viscosities of fluid. It is found that for the hard-sphere case, our method provides expressions f or the longitudinal and bulk viscosities that agree with Enskog result s.