Emergent facilitation by random constraints in a facilitated random walk model of glass

Lam, Leo S. I., Deng, Haiyao ORCID: https://orcid.org/0000-0001-6065-483X, Zhang, Wei-Bing, Nwankwo, Udoka, Xiao, Chu, Yip, Cho-Tung, Lee, Chun-Shing, Ruan, Haihui and Lam, Chi-Hang 2025. Emergent facilitation by random constraints in a facilitated random walk model of glass. Physical Review E (statistical, nonlinear, biological, and soft matter physics) 111 (4) , 044120. 10.1103/PhysRevE.111.044120

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Abstract

The physics of glass has been a significant topic of interest for decades. Dynamical facilitation is widely believed to be an important characteristic of glassy dynamics, but the precise mechanism is still under debate. We propose a lattice model of glass called the facilitated random walk (FRW). Each particle performs a continuous time random walk in the presence of its own random local kinetic constraints. The particles do not interact energetically. Instead, they interact kinetically with a hopping rate resampling rule under which motions of a particle can randomly perturb the local kinetic constraints of other particles. This dynamic interaction is reversible, following a rate restoration rule. A step-by-step reversal of the particle motions exactly restores the previous constraints, modeling randomness quenched in the configuration space of glass. The model exhibits stretched exponential relaxation and dynamical heterogeneity typical of glasses. Despite the lack of an explicit facilitation rule, the FRW shows facilitation behaviors closely analogous to those of the kinetically constrained models (KCM). The FRW is a coarse-grained version of the distinguishable particle lattice model (DPLM) and this exemplifies that compatible defect and atomistic models can complement each other in the study of glass.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Schools > Physics and Astronomy
Publisher:	American Physical Society
ISSN:	2470-0045
Date of First Compliant Deposit:	16 April 2025
Date of Acceptance:	12 March 2025
Last Modified:	17 Apr 2025 11:45
URI:	https://orca.cardiff.ac.uk/id/eprint/177683

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