INTERATOMIC FORCE-FIELDS FOR SILICAS, ALUMINOPHOSPHATES, AND ZEOLITES - DERIVATION BASED ON ABINITIO CALCULATIONS

A consistent force field for the description of interatomic interactions within silicas, aluminophosphates, and zeolites 1 is presented. The derivation of parameters is based both on a fit to the potential-energy surface of small clusters, as determined by ab initio quantum-chemical methods, and on fitting of experimental data on alpha-quartz. It is shown that both types of data are essential for the development of an accurate and transferable force field. The accuracy and transferability of the force field is assessed by comparing force-field predictions for the structure and elastic properties of a dozen different systems with experiment. Results obtained with the present approach compare favorably with those obtained with force fields used in the literature. Moreover, the introduction of additional chemical elements into the force field does not seriously affect the accuracy, making these force fields a valuable tool for the modeling of chemically complex zeolites.