Going for Gold(-Standard): Attaining Coupled Cluster Accuracy in Oxide-Supported Nanoclusters

Abstract

Metal nanoclusters supported on oxide surfaces are widely-used catalysts that boasts sharply enhanced activity over their bulk, especially for the coinage metals: Au, Ag and Cu. These properties depend sensitively on the nanocluster structure, which are challenging to model with density functional theory (DFT) -- the workhorse modelling technique. Leveraging the recently developed SKZCAM protocol, we perform the first ever benchmark study of coinage metal structures on the MgO surface with coupled cluster theory [CCSD(T)] -- the gold-standard modelling technique. We investigate a comprehensive range of DFT models (exchange-correlation functional and dispersion correction) and our benchmarks reveal that none of the investigated models can accurately describe this system. We demonstrate that this arises from inadequate account of metal-metal interactions in the nanocluster and propose a high-level correction which provides reference accuracy at low cost. This forges a path towards studying larger systems, which we highlight by benchmarking Au$_{20}$ on MgO, a challenging system where DFT models have disagreed on its ground state structure.Comment: Working pape