Trends in adsorption of noble gases He, Ne, Ar, Kr, and Xe on Pd(111)(√3 x √3)R30o: All-electron density-functional calculations

It was recently found from <em>ab initio</em> investigations [J. L. F. Da Silva et al., Phys. Rev. Lett. <b>90</b>, 066104 (2003)] that polarization effects and the site dependence of the Pauli repulsion largely dictate the nature of the interaction and the site preference of Xe adatoms on close-packed metal surfaces. It is unclear if the same interaction mechanism occurs for all rare-gas atoms adsorbed on such surfaces. To address this question, we perform all-electron density-functional theory calculations with the local-density approximation (LDA) and generalized gradient approximations (GGA) for [He, Ne, Ar, Kr, and Xe]/Pd(111) in the )-(√3 x √3)R30° structure. Our results confirm that polarization effects of the rare-gas adatoms and Pd atoms in the topmost surface layer, together with the site-dependent Pauli repulsion, largely determine the interaction between rare-gas atoms and the Pd(111) surface. Similar to the earlier ab initio study, the on-top site preference is obtained by the LDA for all rare-gas adatoms, while the GGA functionals yield the on-top site preference for Xe, Kr, and He adatoms, but the fcc site for Ne and Ar