Surface core-level shift of an oxygen-adsorbed W(110) surface

The (1x1) structure observed in the oxygen-atom adsorbed W(110) surface is studied by using the all-electron atomic-force full-potential linear augmen ted plane wave approach. The optimized surface geometry including the oxyge n adatoms and the surface W atoms is consistent with a recent X-ray photoel ectron diffraction (XPD) experiment. The 4f core-level shift of the surface W atom calculated within the initial-state approximation is +0.60 eV, bein g in good agreement with the XPD result (+0.73 eV). The electronic origins of the core-level shift are discussed in terms of intra- and extra-atomic c ontributions to the Madelung potential and their interesting oxygen-height dependence is found. (C) 1999 Elsevier Science B.V. All rights reserved.