Pd3 and Pt3 species on the α-Al2O3(0 0 0 1) surface: cluster models embedded in an elastic polarizable environment

Adsorption of small metal particles Pd3 and Pt3 on an Al-terminated surface α-Al2O3(0 0 0 1) was studied by means of all-electron scalar relativistic density functional calculations. We employed stoichiometric model clusters and our recently developed embedding scheme which accurately accounts for the adsorption-induced substrate relaxation. We compared M3 particles oriented parallel to and almost upright on the surface. The calculations show upright species which interact with two O anions and are stabilized by nearby Al cations to be most stable, with adsorption energies of 1.5 eV (Pd3) and 2.6 eV (Pt3). We also discuss the important role of substrate rearrangement.