Structures, stabilities, and magnetic properties of Cu-doped ZnnOn (n = 3, 9, 12) clusters: A theoretical study

The structural, electronic, and magnetic properties of Cu-doped ZnnOn (n = 3, 9, 12) clusters have been studied using spin-polarized density functional theory. We firstly investigate the lowest-energy structures of pure ZnnOn (n = 1–13) clusters based on the extensive searching, and identify that the Zn3O3, Zn9O9 and Zn12O12 clusters possess relatively higher stability. Then, these stable clusters are taken as candidates for investigating the effect of Cu-atom doping. Three doping modes, that is, substitutional, exohedral, and endohedral doping, are considered. It is found that the substitutional mono- and bi-doped clusters are the most stable among doped clusters. The HOMO–LUMO gaps of the doped clusters are all reduced due to the p–d hybridization caused by the Cu-atom doping. For the monodoped clusters, all isomers have a magnetic moment of 1 μB, which is mainly contributed by the Cu 3d and Cu-surrounding O 2p states. However, for the bidoped clusters, the ground states have zero magnetic moment with the spins on the Cu atoms being either antiferromagnetically coupled or completely quenched, except for Cu2ZnO3 cluster.