The physical properties of adsorption and co-adsorption properties of CO and O₂ molecules on the MgO-supported Pd and Cu atoms have been studied at the DFT/B3LYP level of theory using the embedded cluster model. The calculations show that the supported Pd atom on the perfect surface is energetically more favorable for adsorbing a CO molecule than an O₂ molecule, with the respective binding energies of 206.5 vs. 84.8 kJ/mol. While such interactions on Pd atom located above an oxygen vacancy of the MgO(100) surface are very weak, due to significant amount of electron charge transferring from the vacancy to Pd atom. In contrast, the supported Cu atom on both types of surfaces prefers to adsorb O₂ molecule, instead of CO molecule, with the O₂ binding energies of 140～155 kJ/mol. It was found that the binding between the two-coadsorbates for CO＋CO, CO＋O₂, O₂＋O₂ coadsorbed on the supported Pd atom on the perfect surface reduced the admolecule-Pd interactions by the reductive energies of 46～96 kJ/mol. Such reductions only for O₂＋O₂ coadsorbed on the supported Cu atom on both surfaces are considerable with the reductive energies of 50～71 kJ/mol.

Key words: DFT/B3LYP method, embedded cluster model, Pd(Cu)/MgO surface, oxygen vacancy, CO/O₂ adsorption and coadsorption