Gamma-point density functional calculations on the adsorption of rhodium and palladium particles on MgO(001) surface and their reactivity

We have performed periodic density functional calculations on the adsorption of transition-metal atoms (Rh and Pd) on MgO(001) support. The chemical properties of the supported metal atoms were examined by calculating the adsorption of NO and NO, on the metal atoms. Sampling only the k=0 wavevector point in the Brillouin zone we solved the one-particle Schrodinger equations within the Kohn-Sham framework, employing a unit cell which contained 16 surface atoms and the adsorbate particles. We have found that the interaction between the support surface and the adsorbing metal atom is stronger for Rh than Pd by 1 eV using non-local density approximation. The difference is explained by considering the endothermic reorganizations in the metal electronic structures due to the adsorption. The NO adsorption demonstrated the cationic nature of the adsorbed metal particles and showed that supported Rh atoms can form stronger bond with NO than supported Pd atoms. The NO, adsorption also showed stronger Rh-N interactions and the asymmetric orientation of NO2 suggested weak additional interaction between the ligand and the support surface.