Mechanochemical stability of sub-nm ZnO chains

Formation of monoatomic chains by axial stretching of zinc oxide nanowires is investigated using molecular dynamics and supported by density functional calculations. Special focus is made on the mechanical properties of these structures. Using a state-of-the-art force field it was found that O2 species are commonly formed within the chain. This species drastically weakens the chain strength. Previous simulations, based on a pair potential, failed to predict O2 formation. Moreover, the superductility of zinc oxide nanowires observed in earlier studies, was found to be an artifact of the pair potential. Simulations revealed that the chain length before rupture (usually of 6 atoms) is independent of the nanowire diameter. The electronic structure and the charge distribution of the chains were also studied.