Cooperative jumps and hop-back motion in supercooled liquids near the glass transition in binary colloids

Abstract

Brownian Dynamics simulations on binary charged colloids have been performed to get a liquid to crystal (at volume fraction Φ = 0.2) or glass (Φ = 0.3) as the temperature is lowered. The subdiffusive and staircase behaviours of the mean-squared displacements as well as the behaviour of van-Hove self-correlation functions for the supercooled liquid with Φ = 0.3 indicate strongly cooperative particle motion. The van-Hove distinct correlations follow a factorization property predicted by the mode-coupling theory. Most interestingly, a few particles show an interconnected cooperative hop and subseqent hop-back motion very close to the glass transition.