Classical mechanical isothermal molecular dynamics simulations are used to model Xe atoms and Xe-N clusters trapped in the intracrystalline cavities of zeolite NaA, which is represented as a single alpha cage. An adsorption site model provides a means to investigate the nature of Xe atom adsorption, the site occupancy, and the rate of site-to-site exchange. Chemical shifts are computed for Xe-129 in the cavities, for single Xe atoms through clusters of Xe-9, from 150 to 420 K. An explanation is proposed for the large increase with N in the chemical shift from Xe-6 to Xe-7.