Theoretical study of the adsorption of carbon monoxide on a NaCl (100) surface

Abstract

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 remain close to those of the gas phase. In the present study we report ab initio Hartree-Fock self-consistent field (SCF) and correlated calculations 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 ions embedded in an array of point charges. We have taken into account the basis set superposition error (BSSE) in the supermolecule calculations. This error has a significant effect and cannot be ignored. An effective core potential (ECP) description has been employed for the Na and Cl atoms, in which only the valence electrons are considered explicitly. Morokuma analysis was performed to analyze the SCF binding energy for the CO/NaCl (100) system in terms of physically meaningful components. Electron correlation was studied using MP2 and the Lee-Yang-Parr 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.