Computer Simulations of Supercooled Liquids and Glasses

TL;DR

This paper reviews computer simulations of supercooled liquids and glasses, comparing fragile and strong glass formers, and explores their dynamics near the glass transition, highlighting differences in transport mechanisms and the role of activated processes.

Contribution

It provides a comparative analysis of simulation results for fragile and strong glass formers, linking their dynamics to mode-coupling theory and activated processes, and discusses simulations below the glass transition.

Findings

Fragile glass formers follow mode-coupling theory closely.

Strong glass formers are dominated by activated processes.

Simulations below T_g may connect structural and spin glasses.

Abstract

After a brief introduction to the dynamics of supercooled liquids, we discuss some of the advantages and drawbacks of computer simulations of such systems. Subsequently we present the results of computer simulations in which the dynamics of a fragile glass former, a binary Lennard-Jones system, is compared to the one of a strong glass former, SiO_2. This comparison gives evidence that the reason for the different temperature dependence of these two types of glass formers lies in the transport mechanism for the particles in the vicinity of T_c, the critical temperature of mode-coupling theory. Whereas the one of the fragile glass former is described very well by the ideal version of mode-coupling theory, the one for the strong glass former is dominated by activated processes. In the last part of the article we review some simulations of glass formers in which the dynamics below the glass transition temperature was investigated. We show that such simulations might help to establish a connection between systems with self generated disorder (e.g. structural glasses) and quenched disorder (e.g. spin glasses).