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

► ZnnOn and Cu-doped ZnnOn clusters are theoretically investigated. ► ZnnOn (n = 3, 9, 12) clusters are found to possess relatively higher stability. ► Three (substitutional, exohedral, and endohedral) doping modes are considered. ► The monodoped clusters are all magnetic and magnetism is mainly contributed by the Cu 3d states. ► For the bidoped cases, the ground states are nonmagnetic except for Cu2ZnO3 cluster.