Dynamics of adsorbates in micropores of zeolites and breakdown of Arrhenius behavior

Abstract
A molecular-dynamics calculation of diffusion of xenon in the micropores of zeolite Y shows several unusual features. Xenon atoms migrating from one cage to another through a twelve-membered ring exhibit a temperature-dependent barrier height and a breakdown of Arrhenius behavior. Barrierless trajectories for cage-to-cage migration have been found. The mechanism of migration as a function of temperature is discussed. The activation-energy spectra show the existence of both positive and negative barrier heights.