Periodic density functional study of Rh and Pd interaction with the (1Â 0Â 0)MgO surface

The adsorption geometry and electronic properties of palladium and rhodium atoms deposited on the regular (1 0 0)MgO surface were analyzed by means of periodic DFT calculations using local, gradient-corrected and hybrid (B3LYP) functionals. Spin-polarized computations revealed doublet spin state of Rh atom to be the most stable electronic state for the adsorbed rhodium atom on (1 0 0)MgO. The preferred adsorption site of the metal (Pd and Rh) atoms was found to be the site on top of the surface oxygen atoms. A relatively stable geometry for the adsorption of the Pd and Rh in a bridge position above the two surface oxygens was found as well. The electronic structures suggested partly covalent bonding with contribution from electrostatic attraction between the metal and the oxygen atoms for both optimized structures. Small charge transfer was obtained from the support to the Pd and Rh metal atoms. The calculations showed that rhodium was bound stronger to the substrate probably due to stronger polarization effects.