Journal of Statistical Physics, Vol. 57, Nos. 3/4, 1989, p. 473-482.
The decay of the collisional contribution to the shear-stress autoeorrelation function is shown to be inconsistent with a t -3/2 inverse-power law. The decay of the self part (a combination of pair and triplet correlations) indicates a stretched-exponential decay with a density-independent exponent. The pair contribution by itself also shows stretched-exponential behavior in both two and three dimensions, with different, but still density-independent, exponents. At very long times this stretched-exponential decay of the pair correlations switches over to an algebraic decay, consistent with the diffusional separation of pairs of particles.