A QM/MM approach for the study of monolayer-protected gold clusters

TL;DR

This paper introduces a hybrid QM/MM method for studying thiolated gold clusters, enabling accurate structural and electronic analysis with significantly reduced computational costs compared to full quantum calculations.

Contribution

The paper develops and implements a novel QM/MM approach tailored for monolayer-protected gold clusters, validated against crystallographic data and NMR calculations.

Findings

QM/MM maintains qualitative NMR features of full DFT

Significant computational efficiency gains

Validated against crystallographic data

Abstract

We report the development and implementation of hybrid methods that combine quantum mechanics (QM) with molecular mechanics (MM) to theoretically characterize thiolated gold clusters. We use, as training systems, structures such as Au25(SCH2-R)18 and Au38(SCH2-R)24, which can be readily compared with recent crystallographic data. We envision that such an approach will lead to an accurate description of key structural and electronic signatures at a fraction of the cost of a full quantum chemical treatment. As an example, we demonstrate that calculations of the 1H and 13C NMR shielding constants with our proposed QM/MM model maintain the qualitative features of a full DFT calculation, with an order-of-magnitude increase in computational efficiency.