Structure and structure relaxation

TL;DR

This paper introduces a discrete-dynamics model based solely on a system's equilibrium structure to describe glassy dynamics, aligning with mode-coupling theory and clarifying the concept of structural relaxation.

Contribution

It provides a new discrete-dynamics model that captures glassy dynamics from equilibrium structure, linking it directly to mode-coupling theory results.

Findings

Model reproduces mode-coupling theory results

Decay of density fluctuations described by Debye processes

Long-time dynamics identified as structural relaxation

Abstract

A discrete--dynamics model, which is specified solely in terms of the system's equilibrium structure, is defined for the density correlators of a simple fluid. This model yields results for the evolution of glassy dynamics which are identical with the ones obtained from the mode-coupling theory for ideal liquid--glass transitions. The decay of density fluctuations outside the transient regime is shown to be given by a superposition of Debye processes. The concept of structural relaxation is given a precise meaning. It is proven that the long-time part of the mode-coupling-theory solutions is structural relaxation, while the transient motion merely determines an overall time scale for the glassy dynamics.