Growing Correlation Length on Cooling Below the Onset of Caging in a Simulated Glass-Forming Liquid

TL;DR

This study uses molecular dynamics simulations to analyze higher-order density correlations in a glass-forming liquid, revealing that the correlation length grows significantly below the onset of caging as temperature approaches the mode coupling point.

Contribution

It introduces a fourth-order, time-dependent density correlation function to measure higher-order correlations in a simulated glass-forming liquid.

Findings

Correlation length peaks at a maximum over time.

Correlation length increases as temperature approaches mode coupling temperature.

Higher-order correlations extend beyond static pair correlations.

Abstract

We present a calculation of a fourth-order, time-dependent density correlation function that measures higher-order spatiotemporall correlations of the density of a liquid. From molecular dynamics simulations of a glass-forming Lennard-Jones liquid, we find that the characteristic length scale of this function has a maximum as a function of time which increases steadily beyond the characteristic length of the static pair correlation function $g(r)$ in the temperature range approaching the mode coupling temperature from above.