Dynamic Decay and Superadiabatic Forces in the van Hove Dynamics of Bulk Hard Sphere Fluids

TL;DR

This paper investigates the decay mechanisms of the van Hove function in dense hard sphere fluids using simulations and dynamic density functional theory, revealing general decay processes and the role of superadiabatic forces.

Contribution

It introduces a combined simulation and theoretical approach to analyze decay mechanisms and superadiabatic forces in dense overdamped liquids.

Findings

Decay mechanisms include shell deconfinement, shell decay, and shell drift.

Power functional approximation accurately predicts long-time self diffusion.

Results suggest decay mechanisms are general across similar dense liquids.

Abstract

We study the dynamical decay of the van Hove function of Brownian hard spheres using event-driven Brownian dynamics simulations and dynamic test particle theory. Relevant decays mechanisms include deconfinement of the self particle, decay of correlation shells, and shell drift. Comparison to results for the Lennard-Jones system indicates the generality of these mechanisms for dense overdamped liquids. We use dynamical density functional theory on the basis of the Rosenfeld functional with self interaction correction. Superadiabatic forces are analysed using a recent power functional approximation. The power functional yields a modified Einstein long-time self diffusion coefficient in good agreement with simulation data.