Geometric and electronic properties of gold clusters doped with a single oxygen atom

The adsorption behaviour of a single O atom on Au_n^q clusters (n = 1-8, q = 0, ±1) was systematically investigated by DFT calculations. Both hybrid and pure GGA functionals (B3LYP and PBE) were used to provide reliable conclusions. The most stable structures of Au_nO^q clusters were obtained by using global optimizations with a genetic algorithm. Cationic clusters tend to become three-dimensional for large clusters, as for Au₈O⁺. The binding of O in Au_nO^q clusters is quite strong, especially in the anionic clusters. The O atom can be bound to one, two, or three Au atoms, obtaining nearly one electron from gold atoms. Similarities have been found between Au_nO^q and Au_n+1^q in terms of geometric structures and binding energies. Frontier molecular orbitals and the distribution of unpaired spin density on the O atom were discussed, both of which have a close relationship with the activity of the clusters.