Computational study of molecular hydrogen in zeolite Na-A. I. Potential energy surfaces and thermodynamic separation factors for {ital ortho} and {ital para} hydrogen
- Department of Physics and Astronomy, Swarthmore College, Swarthmore, Pennsylvania 19081 (United States)
- Department of Chemistry, Boston University, Boston, Massachusetts 02215 (United States)
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
We simulate H{sub 2} adsorbed within zeolite Na-A. We use a block Lanczos procedure to generate the first several (9) rotational eigenstates of the molecule, which is modeled as a rigid, quantum rotor with an anisotropic polarizability and quadrupole moment. The rotor interacts with Na cations and O anions; interaction parameters are chosen semiempirically and the truncation of electrostatic fields is handled with a switching function. A Monte Carlo proceedure is used to sample a set of states based on the canonical distribution. Potential energy surfaces, favorable adsorbtion sites, and distributions of barriers to rotation are analyzed. Separation factors for {ital ortho{endash}para}hydrogen are calculated; at low temperatures, these are controlled by the ease of rotational tunneling through barriers. {copyright} {ital 1999 American Institute of Physics.} thinsp
- OSTI ID:
- 686855
- Journal Information:
- Journal of Chemical Physics, Vol. 111, Issue 16; Other Information: PBD: Oct 1999
- Country of Publication:
- United States
- Language:
- English
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