Melting of icosahedral gold nanoclusters from molecular dynamics simulations

TL;DR

This study uses molecular dynamics simulations to investigate the melting behavior of gold nanoclusters, revealing surface softening and shape evolution near melting temperature.

Contribution

It provides detailed insights into the surface dynamics and shape changes of gold nanoclusters during melting, which were not previously characterized in such detail.

Findings

Surface facets soften but do not premelt below melting point

Vertex and edge atom mobility increase with temperature

Clusters become nearly spherical at melting

Abstract

Molecular dynamics simulations show that gold clusters with about 600--3000 atoms crystallize into a Mackay icosahedron upon cooling from the liquid. A detailed surface analysis shows that the facets on the surface of the Mackay icosahedral gold clusters soften but do not premelt below the bulk melting temperature. This softening is found to be due to the increasing mobility of vertex and edge atoms with temperature, which leads to inter-layer and intra-layer diffusion, and a shrinkage of the average facet size, so that the average shape of the cluster is nearly spherical at melting.