Trends in adsorption of noble gases He, Ne, Ar, Kr, and Xe on Pd„111...„ 3Ã 3...R30°: All-electron density-functional calculations

It was recently found from ab initio investigations J. L. F. Da Silva et al., Phys. Rev. Lett. 90, 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 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.