Hard spheres at a planar hard wall: Simulations and density functional theory

TL;DR

This study combines high-precision molecular dynamics simulations and density functional theory to analyze hard sphere fluids near a planar hard wall, providing benchmark data and revealing areas of agreement and deviation.

Contribution

It offers new benchmark simulation data for hard sphere fluids at a wall and compares these with advanced density functional theory predictions.

Findings

Good overall agreement between simulations and theory

Deviations increase at high bulk densities

Provides detailed density profiles and thermodynamic quantities

Abstract

Hard spheres are a central and important model reference system for both homogeneous and inhomogeneous fluid systems. In this paper we present new high-precision molecular-dynamics computer simulations for a hard sphere fluid at a planar hard wall. For this system we present benchmark data for the density profile $\rho(z)$ at various bulk densities, the wall surface free energy $\gamma$, the excess adsorption $\Gamma$, and the excess volume $v_{ex}$, which is closely related to $\Gamma$. We compare all benchmark quantities with predictions from state-of-the-art classical density functional theory calculations within the framework of fundamental measure theory. While we find overall good agreement between computer simulations and theory, significant deviations appear at sufficiently high bulk densities.