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 adso rption of transition-metal atoms (Rh and Pd) on MgO(001) support. The chemical properties of the supported metal atoms were examined by calc ulating 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-part icle Schrodinger equations within the Kohn-Sham framework, employing a unit cell which contained 16 surface atoms and the adsorbate particle s. 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 considerin g the endothermic reorganizations in the metal electronic structures d ue to the adsorption. The NO adsorption demonstrated the cationic natu re of the adsorbed metal particles and showed that supported Rh atoms can form stronger bond with NO than supported Pd atoms. The NO, adsorp tion also showed stronger Rh-N interactions and the asymmetric orienta tion of NO2 suggested weak additional interaction between the ligand a nd the support surface.