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The Central cell model: a mesoscopic hopping model for the study of the displacement autocorrelation function

Pazzona, Federico Giovanni and Gabrieli, Andrea and Pintus, Alberto M. and Demontis, Pierfranco and Suffritti, Giuseppe Baldovino (2011) The Central cell model: a mesoscopic hopping model for the study of the displacement autocorrelation function. The Journal of Chemical Physics, Vol. 134 (18), p. 184109/1-14. eISSN 1089-7690. Article.

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DOI: 10.1063/1.3587618

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.

Item Type:Article
ID Code:6681
Status:Published
Refereed:Yes
Uncontrolled Keywords:Cellular automata, diffusion, lattice gas, mesoporous materials, numerical analysis, probability
Subjects:Area 03 - Scienze chimiche > CHIM/02 Chimica fisica
Divisions:002 Altri enti e centri di ricerca del Nord Sardegna > INSTM-Consorzio Interuniversitario Nazionale per la Scienza e la Tecnologia dei Materiali, Unità di ricerca di Sassari
001 Università di Sassari > 01 Dipartimenti > Chimica
Publisher:American Institute of Physics
eISSN:1089-7690
Deposited On:24 Nov 2011 17:36

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