Nonergodicity parameters of confined hard-sphere glasses

TL;DR

This paper combines mode-coupling theory, density functional theory, and simulations to analyze the nonergodicity parameters of confined hard-sphere glasses, revealing how static structure influences glassy dynamics.

Contribution

It develops a comprehensive theoretical framework for predicting nonergodicity parameters in confined glasses, validated by molecular dynamics simulations.

Findings

Qualitative agreement between theory and simulations for nonergodicity parameters.

Correlation of nonergodicity parameters with in-plane static structure factors.

Identification of subtle effects in higher mode-indices and a criterion for reentrant behavior.

Abstract

Within a recently developed mode-coupling theory for fluids confined to a slit we elaborate numerical results for the long-time limits of suitably generalized intermediate scattering functions. The theory requires as input the density profile perpendicular to the plates, which we obtain from density functional theory within the fundamental-measure framework, as well as symmetry-adapted static structure factors which can be calculated relying on the inhomogeneous Percus-Yevick closure. Our calculations for the nonergodicity parameters for both the collective as well as for the self motion are in qualitative agreement with our extensive event-driven molecular dynamics simulations for the intermediate scattering functions for slightly polydisperse hard-sphere systems at high packing fraction. We show that the variation of the nonergodicity parameters as a function of the wavenumber correlates with the in-plane static structure factors, while subtle effects become apparent in the structure factors and relaxation times of higher mode-indices. A criterion to predict the multiple reentrant from the variation of the in-plane static structure is presented.