Diffusion on a solid surface: Anomalous is normal

TL;DR

This paper numerically investigates classical particles diffusing on solid surfaces, revealing that anomalous diffusion arises naturally from ordinary thermal noise and is controlled by friction, with diverse transport regimes observed.

Contribution

It demonstrates that anomalous diffusion on solid surfaces can be explained by standard Langevin dynamics, highlighting the role of friction in controlling transport regimes.

Findings

Anomalous diffusion is observed in the model.

Friction coefficient controls the diffusion regime.

Anomalous behavior emerges from Maxwell-Boltzmann statistics.

Abstract

We present a numerical study of classical particles diffusing on a solid surface. The particles' motion is modeled by an underdamped Langevin equation with ordinary thermal noise. The particle-surface interaction is described by a periodic or a random two dimensional potential. The model leads to a rich variety of different transport regimes, some of which correspond to anomalous diffusion such as has recently been observed in experiments and Monte Carlo simulations. We show that this anomalous behavior is controlled by the friction coefficient, and stress that it emerges naturally in a system described by ordinary canonical Maxwell-Boltzmann statistics.