Rotational velocity autocorrelation function of interacting Brownian particles

Recently, Hagen, Frenkel and Lowe [Physica A 272 (1999) 376] have obtained interesting simulation data for the rotational velocity autocorrelation function of a selected particle in a dense suspension of interacting spherical Brownian particles. Although a wide time interval was studied, it was found that the correlation function had not yet settled down to its t−5/2 long-time tail at the longest time considered. In the following analysis, the method of Padé approximants is applied to the Laplace transform of the correlation function. A different value for the coefficient of the long-time tail is obtained than found by Hagen et al. by extrapolation. A prediction is made for the behavior of the correlation function outside the range of presently available data.