Regensburg 2007 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 30: Poster II

DY 30.8: Poster

Thursday, March 29, 2007, 16:00–18:00, Poster D

Implications of mean field and non-mean field effects for a system of interacting particles — •Radha Banhatti, Klaus Funke, and Andreas Heuer — Universität Münster, Institut für Physikalische Chemie und SFB 458, Corrensstrasse 30, D-48149 Münster

Recently, a simple harmonic model (SHM) was formulated for an equilibrated system of mutually interacting N +1 particles to study the relaxation following the jump of a central particle at time t=0 [M. Kunow and A. Heuer, J. Chem. Phys. 119, 2338 (2003)]. The relaxation of the central particle (single-particle route) and that of the other N particles (multi-particle route) were cast in the form of rate equations. The SHM formalism was an attempt to enquire into the general validity of the rate equations formulated within jump relaxation models to understand the frequency-dependent conductivity in different classes of disordered materials including ionic crystals, conductors, inorganic glasses and ionic liquids. Using the formalism of the SHM, we show that it is possible to explicitly examine the effect of mean field (collective response) and non-mean field (distance-dependent response) nature of the neighborhood interactions with the central particle. The change in the shape of the trajectory of the central particle (the single-particle route) yields, for example, a direct correlation to the abrupt change of shape of the ion-conductivity spectra of a supercooled melt, calcium potassium nitrate of composition 0.4Ca(NO₃)₂ · 0.6 KNO₃, around T = 375 K [K.Funke and R. D. Banhatti, Solid State Ionics, 177, 1551 (2006)]. A coherent description for the ion conduction in this regime is discussed.