Back to Search Start Over

The central cell model: A mesoscopic hopping model for the study of the displacement autocorrelation function.

Authors :
Pazzona, F. G.
Gabrieli, A.
Pintus, A. M.
Demontis, P.
Suffritti, G. B.
Source :
Journal of Chemical Physics. 5/14/2011, Vol. 134 Issue 18, p184109. 14p. 4 Diagrams, 4 Charts, 3 Graphs.
Publication Year :
2011

Abstract

On the mesoscale, the molecular motion in a microporous material can be represented as a sequence of hops between different pore locations and from one pore to the other. On the same scale, the memory effects in the motion of a tagged particle are embedded in the displacement autocorrelation function (DACF), the discrete counterpart of the velocity autocorrelation function (VACF). In this paper, a mesoscopic hopping model, based on a lattice-gas automata dynamics, is presented for the coarse-grained modeling of the DACF in a microporous material under conditions of thermodynamic equilibrium. In our model, that we will refer to as central cell model, the motion of one tagged particle is mimicked through probabilistic hops from one location to the other in a small lattice of cells where all the other particles are indistinguishable; the cells closest to the one containing the tagged particle are simulated explicitly in the canonical ensemble, whereas the border cells are treated as mean-field cells in the grand-canonical ensemble. In the present paper, numerical simulation of the central cell model are shown to provide the same results as a traditional lattice-gas simulation. Along with this a mean-field theory of self-diffusion which incorporates time correlations is discussed. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00219606
Volume :
134
Issue :
18
Database :
Academic Search Index
Journal :
Journal of Chemical Physics
Publication Type :
Academic Journal
Accession number :
60594606
Full Text :
https://doi.org/10.1063/1.3587618