Eur. Phys. J. E (2020) 43: 56
https://doi.org/10.1140/epje/i2020-11983-6

Regular Article

Complexity of plastic instability in amorphous solids: Insights from spatiotemporal evolution of vibrational modes

¹ State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, 100190, Beijing, China
² School of Engineering Science, University of Chinese Academy of Sciences, 101408, Beijing, China

^* e-mail: mqjiang@imech.ac.cn

Received: 5 July 2020
Accepted: 19 August 2020
Published online: 11 September 2020

Abstract

It has been accepted that low-frequency vibrational modes are causally correlated to fundamental plastic rearrangement events in amorphous solids, irrespective of the structural details. But the mode-event relationship is far from clear. In this work, we carry out case studies using atomistic simulations of a three-dimensional Cu₅₀Zr₅₀ model glass under athermal, quasistatic shear. We focus on the first four plastic events, and carefully trace the spatiotemporal evolution of the associated low-frequency normal modes with applied shear strain. We reveal that these low-frequency modes get highly entangled with each other, from which the critical mode emerges spontaneously to predict a shear transformation event. But the detailed emergence picture is event by event and shear-protocol dependent, even for the first plastic event. This demonstrates that the instability of a plastic event is a result of extremely complex multiple-path choice or competition, and there is a strong, elastic interaction among neighboring instability events. At last, the generality of the present findings is shown to be applicable to covalent-bonded glasses.