Calculation of coverage dependence of electronic density of states and binding energy for chemisorbed oxygen on Ni(001)

We present a tight-binding calculation of the electronic local density of states (LDOS) and binding energy for chemisorbed oxygen on a Ni(001) surface at various coverages. The electronic structure is determined by treating explicitly the 4s and 3d electrons and their hybridization for the substrate Ni atoms and the oxygen 2p electrons. The continued-fraction technique is used to determine the LDOS. The obtained LDOS for the p(2 × 2) and c(2 × 2) structures is in good agreement with photoemission measurements. Our calculation shows that with increasing oxygen coverage, the binding energy of oxygen decreases, whereas the charge transfer on oxygen increases. These results are discussed in connection with oxidation of the surface nickel occuring at high coverages.