Hopping in a Supercooled Lennard-Jones Liquid: Metabasins, Waiting Time Distribution, and Diffusion

TL;DR

This study uses computer simulations to analyze how particles in a supercooled Lennard-Jones liquid hop between energy minima called metabasins, revealing that diffusion depends on waiting time distributions with algebraic decay patterns.

Contribution

It uncovers the organization of the energy landscape into metabasins and links diffusion behavior to the distribution of waiting times, providing new insights into glassy dynamics.

Findings

Diffusion modeled as a random walk among metabasins.

Waiting time distribution shows algebraic decay with specific exponents.

Temperature dependence of diffusion is governed by stable basin waiting times.

Abstract

We investigate the jump motion among potential energy minima of a Lennard-Jones model glass former by extensive computer simulation. From the time series of minima energies, it becomes clear that the energy landscape is organized in superstructures, called metabasins. We show that diffusion can be pictured as a random walk among metabasins, and that the whole temperature dependence resides in the distribution of waiting times. The waiting time distribution exhibits algebraic decays: $\tau^{-1/2}$ for very short times and $\tau^{-\alpha}$ for longer times, where $\alpha\approx2$ near $T_c$. We demonstrate that solely the waiting times in the very stable basins account for the temperature dependence of the diffusion constant.