Disentangling defects and sound modes in disordered solids

TL;DR

This paper introduces a novel method to isolate localized defects in disordered solids by filtering vibrational modes, enabling better understanding and prediction of plastic rearrangements.

Contribution

A new high-pass filter-based technique to distinguish localized defects from extended vibrational modes in disordered solids.

Findings

Localized defects predict plastic rearrangements effectively

Defects exhibit specific energy barrier distributions

Method reveals defect properties relevant to plasticity models

Abstract

We develop a new method to isolate localized defects from extended vibrational modes in disordered solids. This method augments particle interactions with an artificial potential that acts as a high-pass filter: it preserves small-scale structures while pushing extended vibrational modes to higher frequencies. The low-frequency modes that remain are "bare" defects; they are exponentially localized without the quadrupolar tails associated with elastic interactions. We demonstrate that these localized excitations are excellent predictors of plastic rearrangements in the solid. We characterize several of the properties of these defects that appear in mesoscopic theory of plasticity, including their distribution of energy barriers, number density, and size, which is a first step in testing and revising continuum models for plasticity in disordered solids.