Theories of Glass Formation and the Glass Transition

TL;DR

This review advocates for focusing on simpler, more realistic models of glass-forming fluids, highlighting recent simulation results and proposing a new interpretation involving topologically ordered clusters to better understand the glass transition.

Contribution

It introduces a new perspective on glass formation by emphasizing simple models and proposing that topologically ordered clusters explain observed behaviors, challenging existing theories.

Findings

Simple polydisperse systems develop long-range order near glass transition

Simulations show Ising-like bond-orientational order in glass-forming systems

Proposed topological cluster alignment explains Ising-like behavior

Abstract

This key-issues review is a plea for a new focus on simpler and more realistic models of glass-forming fluids. It seems to me that we have too often been led astray by sophisticated mathematical models that beautifully capture some of the most intriguing features of glassy behavior, but are too unrealistic to provide bases for predictive theories. As illustrations of what I mean, the first part of this article is devoted to brief summaries of imaginative, sensible, but disparate and often contradictory ideas for solving glass problems. Almost all of these ideas remain alive today, with their own enthusiastic advocates. I then describe numerical simulations, mostly by H. Tanaka and coworkers, in which it appears that very simple, polydisperse systems of hard disks and spheres develop long range, Ising-like, bond-orientational order as they approach glass transitions. Finally, I summarize my recent proposal that topologically ordered clusters of particles, in disordered environments, tend to become aligned with each other as if they were two-state systems, and thus produce the observed Ising-like behavior. Neither Tanaka's results nor my proposed interpretation of them fit comfortably within any of the currently popular glass theories.