Trends in adsorption of noble gases He, Ne, Ar, Kr, and Xe onPd(111)(3×3)R30°: All-electron

Abstract

It was recently found from ab initio investigations ͓J. L. F. Da Silva et al., Phys. Rev. Lett. 90, 066104 ͑2003͔͒ 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 ͑LDA͒ and generalized gradient approximations ͑GGA͒ for ͓He, Ne, Ar, Kr, and Xe͔ / Pd͑111͒ in the ͑ ͱ 3 ϫ ͱ 3͒R30°s tructure. 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 Pd͑111͒ 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.

Van Der Waals-Corrected Density Functional Theory Simulation of Adsorption Processes on Noble-Metal Surfaces: Xe on Ag(111), Au(111), and Cu(111)

“…in particular, for Xe a general tendency is found [6,[8][9][10][11] for adsorption on metallic surfaces in the low-coordination top sites (this behavior is attributed [6,16] to the delocalization of charge density that increases the Pauli repulsion effect at the hollow sites relative to the top site and lifts the potential well upwards both in energy and height).…”

“…Moreover, the adatoms were adsorbed on both sides of the slab: in this way the surface dipole generated by adsorption on the upper surface of the slab is cancelled by the dipole appearing on the lower surface, thus greatly reducing the spurious dipole-dipole interactions between the periodically repeated images (previous DFT-based calculations have shown that these choices are appropriate [9,13,30,63]). …”

“…Typically, in many physisorbed systems GGAs give only a shallow and flat adsorption well at large adparticle-substrate separations, while the LDA binding energy often turns out to be not far from the experimental adsorption energy; however, since it is well known that LDA tends to overestimate the binding in systems with inhomogeneous electron density (and to underestimate the equilibrium distances), the reasonable performances of LDA must be considered as accidental. Therefore, a theoretical approach beyond the DFT-LDA/GGA framework, that is able to properly describe vdW effects is required to provide more quantitative results [9].…”

“…Rare-gas adsorption on many close-packed metal surfaces, such as Ag(111), Al(111), Cu(111), Pd(111), Pt(111),.. have been extensively studied both experimentally [3][4][5][6] and theoretically [6][7][8][9][10][11][12][13][14][15]. Due to the non-directional character of the vdW interactions that should be dominant in physisorption processes, surface sites that maximize the coordination of the rare-gas adsorbate atom are expected to be the preferred ones, thus favoring the hollow adsorption site.…”

Effects of electrode surface roughness on motional heating of trapped ions

“…is obtained, where A n ( k ) is defined through the boundary condition (27) which allows the calculation of G n+1 ( r, v ). After obtaining…”