Thoretical Investigation of Absorptive Oxygen Bonding With Ni(111) Surface

In this work, adsorption of O on Ni(111) surface with p(2×2) configuration and coverage value of 0.25 ML is investigated using Density Functional Theory (DFT). First, using structural optimization gives 1.87 Ǻ and 1.17 Ǻ, respectively for Ni-O bond length and distance of O from the surface. In order to obtain harmonic and anharmonic frequencies of adsorptive bond, distance of O from the surface was statically changed around its minimum value and energy differences are fitted by harmonic and Morse potential models. The results for frequency calculations are in good agreement with experimental data. Also, the Fermi energy of Ni surface is increased by O adsorption which exhibits the charge transfer from O to surface. However, the large electron negativity of O atom reduces its partial positive charge which leads to decrease of mechanical anharmonicity.