XENON DIFFUSION IN ZEOLITE NAY - TRANSITION-STATE THEORY WITH DYNAMICAL CORRECTIONS

The diffusion coefficient for xenon in zeolite NaY at infinite dilutio n is calculated at low temperatures within a hopping model based on ca ge-to-cage migration only. Diffusion is modeled as a sequence of jump events that may consist of several barrier passages. The number of jum p events is calculated from transition-state theory using the potentia l of mean force as a basis. The potential of mean force is more or les s independent of temperature. In the conversion of the jump rate to th e diffusion coefficient, dynamical corrections are taken into account. The mean number of barrier passages per jump event increases signific antly when the temperature is raised. However, the contribution of the dynamical corrections to the activation energy remains small. In the range from 140-210 K, the diffusion coefficients obtained from the hop ping-model are in excellent agreement with corresponding data from con ventional MD simulations.