Shockley-type surface states on low-index faces of Cu-based alloys with polyvalent solutes

The authors consider Shockley-type surface states (SSS) in substitutionally disordered alloys. For this purpose the Green function for the semi-infinite system is obtained by matching the bulk Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) Green function with the free-electron Green function on the bounding surface.The formalism is applied to calculate binding energies and disorder induced smearings of the Y-centred SSS on the (110) surface and the Gamma -centred SSS on the (111) surfaces of Cu, Cu 90 Al 10 , Cu 70 Zn 30 , and Cu 90 Ge 10 . Their theoretical predictions with regard to changes in the binding energy and the disorder induced smearing in Cu 90 Al 10 where corresponding angle-resolved photoemission experiments are available for comparison are in reasonable accord with measurements. Their computations indicate that the binding energy of the SSS in Cu-based alloys will generally increase with increasing electron/atom (e/a) ratio.