Elastic Models for the Non-Arrhenius Relaxation Time of Glass-Forming Liquids

TL;DR

This paper reviews elastic models explaining the non-Arrhenius relaxation times in glass-forming liquids, highlighting their equivalence under Einstein approximation and connecting them to defect and diffusion theories.

Contribution

It clarifies the equivalence of elastic models in the Einstein approximation and links them to established condensed-matter physics concepts.

Findings

Elastic models are equivalent under Einstein approximation.

Connection established between elastic models and defect/diffusion theories.

Provides a unified view of relaxation mechanisms in viscous liquids.

Abstract

We first review the phenomenology of viscous liquids and the standard models used for explaining the non-Arrhenius average relaxation time. Then the focus is turned to the so-called elastic models, arguing that these models are all equivalent in the Einstein approximation (where the short-time elastic properties are all determined by just one effective, temperature-dependent force constant). We finally discuss the connection between the elastic models and two well-established research fields of condensed-matter physics: point defects in crystals and solid-state diffusion.