Chemisorption on a model transition metal : ordered overlayers with C(2 × 2) and (2 × 1) structures

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Abstract
The effect of chemisorption of ordered atomic layers with C(2 x 2) and (2 × 1) structures on the (001) surface of model transition metals is investigated using the Green's function formalism and the phase shift technique. The electronic structure of the metallic substrate is described by the Linear Combination of Atomic Orbital (LCAO) scheme and is obtained by the method developed by Allan and Kalkstein and Soven. For comparison, both the simple cubic and body centred cubic substrate models are used. Each adatom is represented by a single non-degenerate energy level. The adatoms are placed on the surface in both the on-site and centred fourfold-site configurations. The change in the electronic density of states upon chemisorption is calculated within the Newns-Anderson model. It is shown that the effects of the long-range order of the adsorbate layer, adsorption geometries and the band structure of the substrate are of great importance for the electronic structure of the ordered overlayers. In addition, it is shown that there are two kinds of non-bonding states characteristic of the ordered overlayers