First-Principles Studies on the Structural Transition of ZnO Nanowires at High Pressure

The structural transition of ZnO nanowires at high pressures from wurtzite to rocksalt structure has been studied by first-principles density functional calculations using the SIESTA code. The size effect was studied by calculating a series of nanowires with different diameters, and the doping effect was studied by ion substitution. It is found that the critical pressure of structural transition for nanowires is lower than that of the bulk, and it decreases as the diameter of the nanowire decreases. It is also found that Mn doping can reduce the transition pressure. The size effect and doping effect are discussed in terms of the chemical bonding and energies of the nanowires.