The graphics software package Ribbons1 1 Carson, M. Ribbons models of macromolecules. J. Molec. Graphics 1987, 5, 103-109. is used to display isodensity surfaces of Xe atoms adsorbed in the alpha cage of zeolite NaA. The location, size, and shape of the adsorption sites are highly dependent on the loading and the crystal cation content. When the zeolite has a high number of cations, ellipsoidal sites arrange in a cuboctahedron. When the zeolite has fewer cations, cone-shaped sites arrange in an octahedron at low loading, but at high loading the sites become ellipsoidal and new sites form at cuboctahedral positions. The effect of the nature of the adsorption site on the development of a universal adsorption model is discussed.
Bibliographical noteFunding Information:
The authors wish to thank the Minnesota Supercomputer Institute (MSI) for accesst o the Cray X-MP supercomputer and the Silicon Graphic’s Iris4D workstations, P. Van Valkenberg for acquiring Ribbons for use at MSI, M.V. Hughes for graphical support, and the entire MS1 staff for their technical support. This work was partially supported by the ACS Petroleum ResearchF und, the National Science Foundation, MSI, and the University of Minnesota Graduate School Doctoral Dissertation Fellowship Program. The authors of the isosurface generation methodsI have requested that thef ollowing message be included in all derived work: Portions developed at the National Center for Su-percomputingA pplications at the University of Illinois at Urbana-Champaign.
- Monte Carlo
- molecular simulation