Collective dynamics in a glass-former with Mari-Kurchan interactions

TL;DR

This study demonstrates that a simple off-lattice Mari-Kurchan model exhibits realistic glassy dynamics, including collective and heterogeneous behaviors, despite lacking structural motifs and a complex free-energy landscape.

Contribution

It shows that a minimal model with tree-like interactions can reproduce key features of glassy dynamics observed in real supercooled liquids.

Findings

Relaxation dynamics match those of conventional glass-formers.

Presence of collective and heterogeneous dynamics.

No structural motifs or thermodynamic glass transition observed.

Abstract

We numerically study the equilibrium relaxation dynamics of a two-dimensional Mari-Kurchan glass model. The tree-like structure of particle interactions forbids both non-trivial structural motifs and the emergence of a complex free-energy landscape leading to a thermodynamic glass transition, while the finite-dimensional nature of the model prevents the existence of a mode-coupling singularity. Nevertheless, the equilibrium relaxation dynamics is shown to be in excellent agreement with simulations performed in conventional glass-formers. Averaged time-correlation functions display a phenomenology typical of supercooled liquids, including the emergence of an excess signal in relaxation spectra at intermediate frequencies. We show that this evolution is accompanied by strong signatures of collective and heterogeneous dynamics which cannot be interpreted in terms of single particle hopping and emerge from dynamic facilitation. Our study demonstrates that an off-lattice interacting particle model with extremely simple structural correlations displays quantitatively realistic glassy dynamics.