Dependence of tagged-particle motion on size and mass

Abstract
Tagged-particle motion in fluids is studied as a function of size and mass via variational solutions of the repeated-ring and self-consistent repeated-ring equations. For a massive particle, the transition from Boltzmann to Stokes-Einstein behavior is found as the particle radius varies from small to large with respect to the mean free path. New and more complicated effects are found for light particles. The theory appears to provide an explanation of the results of the computer simulation of Alder and Alley on size and mass dependence. DOI: http://dx.doi.org/10.1103/PhysRevA.27.2603 © 1983 The American Physical Society