Dynamic heterogeneity in two-dimensional supercooled liquids: comparison of bond-breaking and bond-orientational correlations

TL;DR

This study compares bond-breaking and bond-orientational correlations in a 2D supercooled liquid, revealing different relaxation times and growth rates of dynamic correlation lengths as temperature decreases.

Contribution

It provides a detailed comparison of bond-breaking and bond-orientational relaxation, highlighting their distinct temperature-dependent behaviors and correlation lengths in supercooled liquids.

Findings

Bond-orientational relaxation time increases faster with decreasing temperature.

Dynamic correlation length for bond-orientational relaxation grows faster than for bond-breaking.

Ensemble-dependent and independent susceptibilities peak near the same time.

Abstract

We compare the spatial correlations of bond-breaking events and bond-orientational relaxation in a model two-dimensional liquid undergoing Newtonian dynamics. We find that the relaxation time of the bond-breaking correlation function is much longer than the relaxation time of the bond-orientational correlation function and self-intermediate scattering function. However, the relaxation time of the bond-orientational correlation function increases faster with decreasing temperature than the relaxation time of the bond-breaking correlation function and the self-intermediate scattering function. Moreover, the dynamic correlation length that characterizes the size of correlated bond-orientational relaxation grows faster with decreasing temperature than the dynamic correlation length that characterizes the size of correlated bond-breaking events. We also examine the ensemble-dependent and ensemble-independent dynamic susceptibilities for both bond-breaking correlations and bond-orientational correlations. We find that for both correlations, the ensemble-dependent and ensemble-independent susceptibilities exhibit a maximum at nearly the same time, and this maximum occurs at a time slightly shorter than the peak position of the dynamic correlation length.