Dynamic Heterogeneities in a Simple Liquid over Different Time Scales

The heterogeneous features of the supercooled state over different time regimes are explored in a self-consistent mode-coupling mode. The exponent a for the mean-square displacement <r(2)(t)> approximately t(a), of a tagged particle is computed. The non-Gaussian parameter alpha(2)(t) shows a peak in the short time regime in addition to a second peak over longer times. The position of the short-time peak in alpha(2)(t) hardly shifts, while that of the other grows with density.