THEORETICAL-STUDY OF THE ADSORPTION OF CARBON-MONOXIDE ON A NACL(100)SURFACE

CO/NaCl (100) has been referred to as a model system for physisorption in which the adsorbed molecules are bound to the substrate mainly by electrostatic interactions and the properties of the adsorbed phase re main close to those of the gas phase. In the present study we report a b initio Hartree-Fock self-consistent field (SCF) and correlated calcu lations for a cluster model of one CO on NaCl (100). The real infinite NaCl (100) surface is modeled by a cluster consisting of Na and Cl io ns embedded in an array of point charges. We have taken into account t he basis set superposition error (BSSE) in the supermolecule calculati ons. This error has a significant effect and cannot be ignored. An eff ective core potential (ECP) description has been employed for the Na a nd Cl atoms, in which only the valence electrons are considered explic itly. Morokuma analysis was performed to analyze the SCF binding energ y for the CO/NaCl (100) system in terms of physically meaningful compo nents. Electron correlation was studied using MP2 and the Lee-Yang-Par r correlation functional. Finally, we investigated the interaction of two parallel CO molecules adsorbed at adjacent sites on the NaCl (100) surface. This interaction was found to be repulsive and unaffected by the presence of the NaCl surface.