An automated cluster surface scanning method for exploring reaction paths on metal-cluster surfaces

Metal-cluster surfaces present a wide variety of unique coordination environments. This complexity makes it difficult to manually probe the surface reactivity of such clusters. Here, we present a simple and automated method to systematically discover reaction pathways on cluster surfaces, based on the automated cluster surface scanning (ACSS) technique for mapping out potential energy surfaces. We showcase our method on 55-atom icosahedral Cu and Ag clusters, where we determine the activation energies of four elementary steps common in heterogeneous catalysis - hydrogen recombination (H* + H* H-2* + *), oxygen recombination (O* + O* -> O-2* + *), water formation (OH* + H* -> H2O* + *), and CO oxidation (CO* + O* CO2* + *) - with density functional theory calculations (DFT-PBE + D3). We show that the ACSS method requires significantly less human effort than the established manually performed climbing-image nudged elastic band (MP + CI-NEB) technique and locates transition states with comparable accuracy (root-mean-squared error of 0.10 eV) and similar computational cost. Rigorous sampling of the potential energy surface with the ACSS method allows one to locate all lowest-energy reaction pathways obtained via the MP+CI-NEB approach, as well as alternative pathways that one may have missed with the MP+CI-NEB approach due to the many possible pathways available on these clusters. The accuracy and efficiency afforded by the ACSS method could enable high-throughput exploration of the diverse reactivity of metal clusters.

Automated summary

A method for systematically discovering reaction pathways on metal-cluster surfaces is proposed, utilizing the ACSS technique to accurately locate transition states with less human effort compared to traditional methods. The rigorous sampling of potential energy surfaces with the ACSS method allows for the discovery of alternative reaction pathways that may have been overlooked with traditional methods, enabling high-throughput exploration of metal-cluster reactivity.