ATOM PAIR POTENTIAL FOR MOLECULAR-DYNAMICS SIMULATIONS OF STRUCTURAL AND DYNAMICAL PROPERTIES OF ALUMINOSILICATES - TEST ON SILICALITE AND ANHYDROUS NA-A AND CA-A ZEOLITES AND COMPARISON WITH EXPERIMENTAL-DATA

An empirical atom pair potential for aluminosilicates including coulom bic interactions explicitly, and suitable for molecular dynamics simul ations, has been tested on an aluminium-free molecular sieve (silicali te) and on the anhydrous aluminium-rich zeolite A, containing Na or Ca cations. This represents a first step towards a realistic potential t hat is able to reproduce the details of the structure and dynamics of aluminosilicates. The results are in reasonable agreement with experim ental data, both structural (taken from the literature) and spectrosco pic (most of which are new). For structures showing disordered extrafr amework ion distributions, point-charge models are insufficiently accu rate and polarization effects should be taken into account. Previously proposed model potentials are discussed.