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 o xide. The surface energies for the {100}, {110}, and Ni {111} surfaces have been calculated as a function of temperature for NiO. The surfac e energies for all three surfaces were essentially constant up to 2000 K, when surface melting was observed for the less densely packed surf aces such as the {110} and Ni {111} surfaces. The {110} surface recons tructed to give {100} microfacets that are densely packed, and hence t he 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 ener gy was negative, indicating that thermodynamically the surface would o xidize.