title: A network of discrete events for the representation and analysis of diffusion dynamics.
abstract: We developed a coarse-grained description of the phenomenology of diffusive processes, in terms of a space of discrete events and its representation as a network. Once a proper classification of the discrete events underlying the diffusive process is carried out, their transition matrix is calculated on the basis of molecular dynamics data. This matrix can be represented as a directed, weighted network where nodes represent discrete events, and the weight of edges is given by the probability that one follows the other. The structure of this network reflects dynamical properties of the process of interest in such features as its modularity and the entropy rate of nodes. As an example of the applicability of this conceptual framework, we discuss here the physics of diffusion of small non-polar molecules in a microporous material, in terms of the structure of the corresponding network of events, and explain on this basis the diffusivity trends observed. A quantitative account of these trends is obtained by considering the contribution of the various events to the displacement autocorrelation function.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Sassari and Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di Ricerca di Sassari, via Vienna, 2, I-07100 Sassari, Italy.
authors.forename: Alberto M
authors.initials: AM
authors.lastname: Pintus
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Sassari and Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di Ricerca di Sassari, via Vienna, 2, I-07100 Sassari, Italy.
authors.forename: Federico G
authors.initials: FG
authors.lastname: Pazzona
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Sassari and Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di Ricerca di Sassari, via Vienna, 2, I-07100 Sassari, Italy.
authors.forename: Pierfranco
authors.initials: P
authors.lastname: Demontis
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Sassari and Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali (INSTM), Unità di Ricerca di Sassari, via Vienna, 2, I-07100 Sassari, Italy.
authors.forename: Giuseppe B
authors.initials: GB
authors.lastname: Suffritti