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DY: Fachverband Dynamik und Statistische Physik

DY 4: Granular Matter / Contact Dynamics Part I

DY 4.4: Vortrag

Montag, 16. März 2015, 10:15–10:30, BH-N 128

Packing of spheres in a flat container and geometrical frustration — Kirsten Harth and •Ralf Stannarius — Otto-von-Guericke-Universität Magdeburg

We study the packing of monodisperse spheres in a flat vertical box with cell gap slightly larger than the particle diameter. The particles form a nearly regular triangular lattice in the cell plane. The additional freedom of a displacement normal to the cell plane places them either at the front or rear cell plate, leading to a denser arrangement in the cell plane, but at the same time to frustrated states (two of three neighboring beads have to occupy the same cell wall). Analogies to order in antiferroelectric Ising spin systems on a triangular lattice and to colloidal assemblies in thin layers are evident. We analyse the packing statistics and compare them to Monte Carlo simulations. By tilting the container from the vertical, we can modify the relative occupation numbers of front and back sites, mimicking an external field similar to magnetic fields in spin systems. The experiment offers both insights in the influence of geometrical constraints on random packing, and a descriptive example of frustrated ordering.