Ab initio calculations of the electronic properties of the nickel oxide surface

Abstract

Self-consistent unrestricted Hartree-Fock calculations are presented for the adsorption of atomic oxygen onto the nickel oxide (100) surface. The perfect surface is shown to be non-reactive, but enhanced binding is found for vacancy sites in the first two atomic layers. Of particular interest are a first layer cation vacancy and a second layer anion vacancy. Various charge states are examined and charge transfers between adsorbate and surface are noted. A calculation for molecular oxygen in the neighborhood of a second layer anion vacancy is also presented. O2 is found to bind to the surface less strongly than atomic oxygen and accordingly a dissociation site is postulated. Analysis of the character of the electrons on the transition metal atom indicates that bonding is localized in the s-and p-character electrons rather than in the d-electrons as has been suggested previously.