Fluctuation dissipation ratio in an aging Lennard-Jones glass

TL;DR

This study uses Molecular Dynamics simulations to investigate the violation of the fluctuation-dissipation theorem in a Lennard-Jones glass, revealing a discontinuous fluctuation-dissipation ratio similar to spin glass models.

Contribution

It provides the first detailed analysis of the fluctuation-dissipation ratio in a Lennard-Jones glass, showing a piecewise constant behavior akin to spin systems with replica symmetry breaking.

Findings

X(C) is best fitted as a discontinuous, piecewise constant function

Results support the similarity between structural glasses and spin systems

Strengthens the conjecture of similar phase space structures

Abstract

By using extensive Molecular Dynamics simulations, we have determined the violation of the fluctuation-dissipation theorem in a Lennard-Jones liquid quenched to low temperatures. For this we have calculated $X(C)$, the ratio between a one particle time-correlation function $C$ and the associated response function. Our results are best fitted by assuming that $X(C)$ is a discontinuous, piecewise constant function. This is similar to what is found in spin systems with one step replica symmetry breaking. This strengthen the conjecture of a similarity between the phase space structure of structural glasses and such spin systems.