Adsorption of Pd atoms and Pd4 clusters on the MgO(001) surface: a density functional study

We performed gradient-corrected density functional calculations on the adsorption of Pd atoms and Pd4 clusters on the MgO(001) surface. The surface was represented by clusters embedded in point charge arrays and total ion model potentials. Pd atoms adsorb on top of the O ions with a binding energy of 0.9±0.1 eV and a distance of 2.2 Å. A Pd4 square cluster is almost perfectly accommodated to the MgO substrate, suggesting a preference for pseudomorphic growth of large Pd particles. PdPd distances are substantially elongated compared to the bulk metal, in agreement with observations on small supported Pd clusters.