Computational study of molecular hydrogen in zeolite Na-A. I. Potential energy surfaces and thermodynamic separation factors for ortho and para hydrogen

Cherry Rose Anderson, David F. Coker, Juergen Eckert, Amy L.R. Bug

Research output: Contribution to journalArticle

39 Scopus citations

Abstract

We simulate H2 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 ortho-parahydrogen are calculated; at low temperatures, these are controlled by the ease of rotational tunneling through barriers.

Original languageEnglish
Pages (from-to)7599-7613
Number of pages15
JournalJournal of Chemical Physics
Volume111
Issue number16
DOIs
StatePublished - Oct 22 1999

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