Understanding the reactivity properties of Au_n (6 ≤ n ≤ 13) clusters using density functional theory based reactivity descriptors

Abstract

Relativistic density functional theory (DFT) based calculations have been performed on gold clusters with six to thirteen atoms (Au_n; n = 6-13). The ground state geometries of these clusters as obtained from our calculations are presented and discussed. This work proposes that atoms in a ground state conformation can be classified into distinct types of reactive sites in a given geometry. Based on symmetry, susceptibility of various types of reactive sites in the ground state geometry toward an impending electrophilic and/or a nucleophilic attack has also been studied using DFT based reactivity descriptors. The studies have also been extended to high energy isomers in these cluster sizes. The reactivity of various sites as a function of cluster size and shape was thus analyzed. The study shows that as a general rule the size and shape of the cluster influences the number and position of available sites for an electrophilic and/or nucleophilic attack. This makes the reactivity patterns of these clusters highly complex. The study also highlights as to how for a cluster with seven atoms (Au₇) various conformations are likely to coexist indicating that the reactivity patterns of various high energy conformations are also important while dealing with small sized Au clusters.