Diffusion of gold nanoclusters on graphite

TL;DR

This study uses molecular dynamics and kinetic Monte Carlo simulations to analyze the diffusion and coalescence of large gold nanoclusters on graphite, revealing their significant mobility and implications for material morphology.

Contribution

It provides new insights into the mobility of large gold nanoclusters and their aggregation behavior on graphite surfaces, combining molecular dynamics with kinetic Monte Carlo methods.

Findings

Large gold clusters diffuse similarly to single adatoms.

Cluster dimers also exhibit high diffusion rates.

Large islands of clusters remain mobile, affecting material structure.

Abstract

We present a detailed molecular-dynamics study of the diffusion and coalescence of large (249-atom) gold clusters on graphite surfaces. The diffusivity of monoclusters is found to be comparable to that for single adatoms. Likewise, and even more important, cluster dimers are also found to diffuse at a rate which is comparable to that for adatoms and monoclusters. As a consequence, large islands formed by cluster aggregation are also expected to be mobile. Using kinetic Monte Carlo simulations, and assuming a proper scaling law for the dependence on size of the diffusivity of large clusters, we find that islands consisting of as many as 100 monoclusters should exhibit significant mobility. This result has profound implications for the morphology of cluster-assembled materials.