MOLECULAR-DYNAMICS SIMULATIONS OF NICKEL-OXIDE SURFACES

Molecular-dynamics-simulation techniques have been used to investigate the effect of temperature on the three low index surfaces of nickel oxide. The surface energies for the {100}, {110}, and Ni {111} surfaces have been calculated as a function of temperature for NiO. The surface energies for all three surfaces were essentially constant up to 2000 K, when surface melting was observed for the less densely packed surfaces such as the {110} and Ni {111} surfaces. The {110} surface reconstructed to give {100} microfacets that are densely packed, and hence the surface disorder was less than the Ni {111} surface. The defective (Ni3+) Ni {111} surface showed a similar tendency but was less marked, partly due to the increased charge at the surface. The oxidation energy was negative, indicating that thermodynamically the surface would oxidize.