The equilibrium probability distribution of N methane molecules adsorbed in the interior of n alpha cages of the ZK4 zeolite, the all-silica analogue of zeolite A, is modeled by a modified hypergeometric distribution where the effects of mutual exclusion between particles are extracted from long molecular dynamics simulations. The trajectories are then analyzed in terms of time-correlation functions for the fluctuations in the occupation number of the alpha cages. The analysis digs out the correlations induced by the spatial distribution of the adsorbed molecules coupled with a migration mechanism where a molecule can pass from one a cage to another, one-by-one. These correlations lead to cooperative motion, which manifests itself as a nonexponential decay of the correlators. Our results suggest ways of developing improved lattice approaches that may be useful for studying diffusion in much larger systems and for a much longer observation time.

Understanding Diffusion in Confined Systems: Methane in a ZK4 Molecular Sieve. A Molecular Dynamics Simulation Study / Demontis, Pierfranco; Fenu, L. A.; Suffritti, Giuseppe Baldovino. - In: JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL. - ISSN 1520-6106. - 109:38(2005), pp. 18081-18087. [10.1021/jp052597g]

Understanding Diffusion in Confined Systems: Methane in a ZK4 Molecular Sieve. A Molecular Dynamics Simulation Study

DEMONTIS, Pierfranco;SUFFRITTI, Giuseppe Baldovino
2005

Abstract

The equilibrium probability distribution of N methane molecules adsorbed in the interior of n alpha cages of the ZK4 zeolite, the all-silica analogue of zeolite A, is modeled by a modified hypergeometric distribution where the effects of mutual exclusion between particles are extracted from long molecular dynamics simulations. The trajectories are then analyzed in terms of time-correlation functions for the fluctuations in the occupation number of the alpha cages. The analysis digs out the correlations induced by the spatial distribution of the adsorbed molecules coupled with a migration mechanism where a molecule can pass from one a cage to another, one-by-one. These correlations lead to cooperative motion, which manifests itself as a nonexponential decay of the correlators. Our results suggest ways of developing improved lattice approaches that may be useful for studying diffusion in much larger systems and for a much longer observation time.
Understanding Diffusion in Confined Systems: Methane in a ZK4 Molecular Sieve. A Molecular Dynamics Simulation Study / Demontis, Pierfranco; Fenu, L. A.; Suffritti, Giuseppe Baldovino. - In: JOURNAL OF PHYSICAL CHEMISTRY. B, CONDENSED MATTER, MATERIALS, SURFACES, INTERFACES & BIOPHYSICAL. - ISSN 1520-6106. - 109:38(2005), pp. 18081-18087. [10.1021/jp052597g]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11388/80537
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