Quantum chemical studies on zeolites and silica

After mentioning differences in CO and SiO bonding and different structural types of silicates, the conclusion that interactions between external partners and surfaces of silica and zeolites are mostly dominated by van der Waals forces is discussed. Consequently, the theoretical treatment includes (i) selection of appropriate cluster models, (ii) application of nonempirical quantum chemical methods for obtaining interaction potentials, and (iii) statistical thermodynamic evaluation of adsorption characteristics. As examples vibrational frequencies of H 2 O and NH 3 adsorbed on cationic sites, the interaction of conjugated hydrocarbons with Na + sites, and the interaction of H 2 O with various sites on silica and zeolite surfaces are considered.