A PM3 THEORETICAL-STUDY OF THE ADSORPTION AND DISSOCIATION OF WATER ON MGO SURFACES

Semiempirical PM3 calculations have been performed on large cluster mo dels, (MgO)(16), in order to study the adsorption and dissociation of water on pure, defective(vacancies) and doped (K, Li, Na, Al) MgO (001 ) surfaces. The geometries of adsorbed and dissociated molecules were optimized in order to analyze total and binding energies, charge trans fer processes, preferential sires of interaction, Mulliken atomic popu lations and charge redistribution, HOMO, orbital and energy gaps. The basic-acidic characteristics of the low coordinated magnesium and oxyg en atoms located at corner and edge sites are analyzed and discussed. The theoretical results are confronted with available experimental dat a. (C) 1998 Elsevier Science B.V.