Free Energy Landscape and Isomerization Rates of Au$_4$ Clusters at Finite Temperature

TL;DR

This study uses advanced molecular simulations to explore the free energy landscape and isomerization rates of Au4 clusters at finite temperature, providing insights into their dynamic structures relevant for catalysis.

Contribution

It introduces a first-principles molecular dynamics approach combined with adaptive biasing force to analyze the dynamic structural properties of Au4 clusters.

Findings

Quantitative understanding of Au4 cluster free energy landscape

Insights into isomerization rates at finite temperature

Application of adaptive biasing force in cluster simulations

Abstract

In metallic nanoparticles, the cluster geometric structures control the particle's electronic band structure, polarizability, and catalytic properties. Analyzing the structural properties is a complex problem; the structure of an assembled cluster changes from moment to moment due to thermal fluctuations. Conventional structural analyses based on spectroscopy or diffraction cannot determine the instantaneous structure exactly and can merely provide an averaged structure. Molecular simulations offer an opportunity to examine the assembly and evolution of metallic clusters, as the preferred assemblies and conformations can easily be visualized and explored. Here, we utilize the adaptive biasing force algorithm applied to first principles molecular dynamics to demonstrate exploration of a relatively simple system which permits comprehensive study of the small metal cluster $\ce{Au4}$ in both neutral and charged configurations. Our simulation work offers a quantitative understanding of these clusters' dynamic structure, which is significant for single-site catalytic reactions on metal clusters and provides a starting point for a detailed quantitative understanding of more complex pure metal and alloy clusters' dynamic properties.