Poitiers, France MgO particles of catalytic interest dissociate water molecules. Recent theoretical studies concluded that the thermodynamically stable 100 surface of MgO is inactive against water dissociation but defects or higher index surfaces could be active. We investigate that problem using an embedded cluster scheme. The geometry of adsorbed water molecules is optimized on several models of MgO surfaces. Correlation effects are taken into account at the MP2 level in some cases.
All calculations use the Gaussian system of programs.
Our results essentially support previous theoretical predictions. The four-coordinated Mg and O are not individually active but chemisorption occurs on the 110 surface.