Alpha-Relaxation Processes in Binary Hard-Sphere Mixtures

TL;DR

This study uses molecular-dynamics simulations to analyze alpha-relaxation in binary hard-sphere mixtures, revealing how mixing influences glassy dynamics and relaxation parameters at high densities.

Contribution

It provides new simulation data on partial-density-fluctuation correlation functions and compares these with mode-coupling theory predictions for glass transitions.

Findings

Alpha-relaxation time varies over four orders of magnitude with compression.

Relaxation parameters depend on wave vector and differ between species.

Results semi-quantitatively agree with mode-coupling theory predictions.

Abstract

Molecular-dynamics simulations are presented for two correlation functions formed with the partial density fluctuations of binary hard-sphere mixtures in order to explore the effects of mixing on the evolution of glassy dynamics upon compressing the liquid into high-density states. Partial-density-fluctuation correlation functions for the two species are reported. Results for the alpha-relaxation process are quantified by parameters for the strength, the stretching, and the time scale, where the latter varies over almost four orders of magnitude upon compression. The parameters exhibit an appreciable dependence on the wave vector; and this dependence is different for the correlation function referring to the smaller and that for the larger species. These features are shown to be in semi-quantitative agreement with those calculated within the mode-coupling theory for ideal liquid-glass transitions.