Relating chaos to deterministic diffusion of a molecule adsorbed on a surface

TL;DR

This paper explores how chaotic internal molecular dynamics influence surface diffusion, demonstrating through models and simulations that internal chaos can significantly affect a molecule's movement on a substrate.

Contribution

It establishes a direct link between internal chaos and molecular diffusion on surfaces, highlighting the role of geometry and internal dynamics in this process.

Findings

Strong chaos can arise from molecular geometry in simple models

Realistic benzene models exhibit internal chaos affecting diffusion

Internal chaos influences the diffusion behavior on graphite

Abstract

Chaotic internal degrees of freedom of a molecule can act as noise and affect the diffusion of the molecule on a substrate. A separation of time scales between the fast internal dynamics and the slow motion of the centre of mass on the substrate makes it possible to directly link chaos to diffusion. We discuss the conditions under which this is possible, and show that in simple atomistic models with pair-wise harmonic potentials, strong chaos can arise through the geometry. Using molecular-dynamics simulations, we demonstrate that a realistic model of benzene is indeed chaotic, and that the internal chaos affects the diffusion on a graphite substrate.