SORPTION OF XENON IN ZEOLITE-RHO - A THERMODYNAMIC SIMULATION STUDY

Molecular dynamics simulations of the sorption of xenon at 360 K in zeolite rho are reported. The xenon-solid potential is taken to be a pairwise sum of xenon-oxide interactions, with parameters adjusted to give agreement with the experimental Henry's law constants. Energies of adsorption and the distributions of sorbed atoms in the cage/window system were evaluated as a function of the xenon loading in the zeolite. It is shown that increasing loading produces an increase in the (negative) xenon-xenon average energy which is compensated by a decrease in the (negative) xenon-solid energy. The atomic distributions show that the xenon atoms are initially tightly sorbed in the cage windows. Once these are filled, additional xenons show chaotic, fluidlike trajectories in the cages. However, at the highest xenon loadings, even the atoms in the cages become localized into an ordered structure.