Analysis of local structure of mechanical and thermal rearrangements in glasses with the atomic cluster expansion

TL;DR

This paper uses the atomic cluster expansion to identify structural signatures of excitations in glasses, revealing that simple two-body correlations suffice for binary mixtures, while polymers need higher-order correlations.

Contribution

It introduces a universal linear basis for atomic environments and demonstrates its effectiveness in distinguishing active and inactive particles in different glass models.

Findings

Binary mixtures are well predicted with two-body correlations.

Polymer glasses require both two- and three-body correlations.

Structural signatures are consistent across activation mechanisms.

Abstract

We explore the structural signatures of excitations in amorphous materials with the atomic cluster expansion (ACE), a universal and complete linear basis of descriptors of the atomic environment. Body-orderd linear classifiers are constructed that distinguish between active and inactive particles in three different model glass formers, in which structural relaxation occurs either through spontaneous thermal activation or by simple shear. We find that in binary mixtures, maximum prediction accuracy is already achieved with very few two-body correlations, while a polymer glass requires both two- and three-body correlations. Trends are robust across both activation mechanisms.