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DF: Fachverband Dielektrische Festkörper

DF 15: Glasses and Glass Transition II (Joint Session of CPP, DY, DF)

DF 15.1: Topical Talk

Donnerstag, 17. März 2011, 10:45–11:15, ZEU 114

Local Anisotropy of Fluids, Glasses and Jammed Bead Packs — •Gerd Schroeder-Turk — Theoretische Physik, Friedrich-Alexander Universität Erlangen-Nürnberg, Staudtstr 7B, 91058 Erlangen

The local structure of particle ensembles is important for physical properties of normal or super-cooled fluids, jammed bead packs or structural glass phases. It is often characterized by order parameters such as q₄ or q₆, defined by spherical harmonics of particle neighborhoods. Here we show that a Minkowski tensor analysis of the particles’ Voronoi cells provides shape indices that give a clear signature of various structural transitions in particle systems. In particular, all of the above mentioned systems consist of locally anisotropic environments. We show that the degree of cell anisotropy shows a clear signature of the jamming transition in bead packs, the transition to partially ordered states at the random close packing limit, and of the transitions from fluid to ordered phases in simple liquids. For jammed bead packs, these findings suggest an inherent geometrical reason why anisotropic shapes can fill space more efficiently than spheres.
[1] Schröder-Turk et al, Europhys. Lett., 90(3), 34001 (2010)
[2] Kapfer et al, J. Stat. Mech. (2010) P11010