Dynamics of fluids in quenched-random potential energy landscapes: a mode-coupling theory approach

TL;DR

This paper uses mode-coupling theory to analyze how fluids behave in quenched-random potential energy landscapes, revealing complex dynamics and non-monotonic diffusion behavior influenced by disorder and density.

Contribution

It provides a theoretical framework for understanding fluid dynamics in disordered landscapes using mode-coupling theory, highlighting the impact of disorder strength and correlation length.

Findings

Self-diffusion coefficient shows non-monotonic behavior with density.

Disorder correlation length significantly affects fluid dynamics.

Theoretical results align with experimental observations.

Abstract

Motivated by a number of recent experimental and computational studies of the dynamics of fluids plunged in quenched-disordered external fields, we report on a theoretical investigation of this topic within the framework of the mode-coupling theory, based on the simple model of the hard-sphere fluid in a Gaussian random field. The possible dynamical arrest scenarios driven by an increase of the disorder strength and/or of the fluid density are mapped, and the corresponding evolutions of time-dependent quantities typically used for the characterization of anomalous self-diffusion are illustrated with detailed computations. Overall, a fairly reasonable picture of the dynamics of the system at hand is outlined, which in particular involves a non-monotonicity of the self-diffusion coefficient with fluid density at fixed disorder strength, in agreement with experiments. The disorder correlation length is shown to have a strong influence on the latter feature.