The nature of slow dynamics in a minimal model of frustration-limited domains

TL;DR

This paper investigates the slow dynamics of a minimal frustration-limited domain model for glass-forming liquids through simulations and theoretical comparisons, revealing differences from typical liquid relaxation behaviors.

Contribution

It demonstrates that the model's relaxation dynamics differ from those of real liquids and shows that a simple Hartree approximation effectively describes the model's relaxation.

Findings

Relaxation times increase non-Arrheniusly near microphase separation.

Structural relaxation remains nearly exponential at each wave vector.

Hartree approximation captures relaxation properties well even near ergodicity loss.

Abstract

We present simulation results for the dynamics of a schematic model based on the frustration-limited domain picture of glass-forming liquids. These results are compared with approximate theoretical predictions analogous to those commonly used for supercooled liquid dynamics. Although model relaxation times increase by several orders of magnitude in a non-Arrhenius manner as a microphase separation transition is approached, the slow relaxation is in many ways dissimilar to that of a liquid. In particular, structural relaxation is nearly exponential in time at each wave vector, indicating that the mode coupling effects dominating liquid relaxation are comparatively weak within this model. Relaxation properties of the model are instead well reproduced by the simplest dynamical extension of a static Hartree approximation. This approach is qualitatively accurate even for temperatures at which the mode coupling approximation predicts loss of ergodicity. These results suggest that the thermodynamically disordered phase of such a minimal model poorly caricatures the slow dynamics of a liquid near its glass transition.