Thermodynamics predicts how confinement modifies hard-sphere dynamics

TL;DR

This study demonstrates that confinement significantly alters the structure and dynamics of hard-sphere fluids, but the relationship between diffusivity, entropy, and density remains consistent, allowing thermodynamic predictions of confined behavior.

Contribution

It shows that thermodynamic relationships can predict how confinement affects fluid dynamics, regardless of channel width or wall interactions.

Findings

Confinement modifies local structure and dynamics.

The relationship between diffusivity, entropy, and density is robust.

Thermodynamics can predict confined fluid behavior.

Abstract

We study how confining the equilibrium hard-sphere fluid to restrictive one- and two-dimensional channels with smooth interacting walls modifies its structure, dynamics, and entropy using molecular dynamics and transition-matrix Monte Carlo simulations. Although confinement strongly affects local structuring, the relationships between self-diffusivity, excess entropy, and average fluid density are, to an excellent approximation, independent of channel width or particle-wall interactions. Thus, thermodynamics can be used to predict how confinement impacts dynamics.