Electronic structure of the (2×2)Cρ4gcarbidic phase on Ni{100}

Angle-resolved photoemission measurements of the valence-electronic structure of the Ni{100}(2×{}2)C structure are compared with the results of self-consistent density-functional calculations of the two-dimensional band structure for a c(2×{}2)C overlayer on Ni{100}. Good agreement is found for the energies of the main C 2p-- and C 2s--related features at {Γ}{} and the computed dispersion is similar to, but somewhat greater than, that observed experimentally. These experimental features map in the c(2×{}2) surface Brillouin zone defined by the carbon overlayer, and not the (2×{}2) zone of the surface reconstruction. Changes in the d band structure are attributed to this reconstruction and are not found in the calculated bands or in experiments on a c(2×{}2)O overlayer, both of which involve unreconstructed surfaces.