A Double-Transition Scenario for Anomalous Diffusion in Glass-Forming Mixtures

TL;DR

This study uses molecular dynamics simulations to explore a binary mixture exhibiting anomalous diffusion and a double-transition scenario involving glass and localization transitions, contrasting simulation results with mode-coupling theory.

Contribution

It introduces a detailed simulation analysis of a double-transition scenario in glass-forming mixtures, highlighting the role of small-particle dynamics and contrasting with theoretical predictions.

Findings

Anomalous power-law diffusion of small particles observed.

Decoupling of species' long-time dynamics demonstrated.

Slowing down of small-particle transport when excluded-volume constraints are removed.

Abstract

We study by molecular dynamics computer simulation a binary soft-sphere mixture that shows a pronounced decoupling of the species' long-time dynamics. Anomalous, power-law-like diffusion of small particles arises, that can be understood as a precursor of a double-transition scenario, combining a glass transition and a separate small-particle localization transition. Switching off small-particle excluded-volume constraints slows down, rather than enhances, small-particle transport. The data are contrasted with results from the mode-coupling theory of the glass transition.