Minkowski tensors and local structure metrics: Amorphous and crystalline sphere packings
Schröder-Turk, G.E., Schielein, R., Kapfer, S.C., Schaller, F.M., Delaney, G.W., Senden, T., Saadatfar, M., Aste, T. and Mecke, K. (2013) Minkowski tensors and local structure metrics: Amorphous and crystalline sphere packings. In: 7th International Conference on Micromechanics of Granular Media: Powder and Grains 2013, 8 - 12 July 2013, Sydney, Australia pp. 349-352.
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Robust and sensitive tools to characterise local structure are essential for investigations of granular or particulate matter. Often local structure metrics derived from the bond network are used for this purpose, in particular Steinhardt's bond-orientational order parameters ql . Here we discuss an alternative method, based on the robust characterisation of the shape of the particles' Voronoi cells, by Minkowski tensors and derived anisotropy measures. We have successfully applied these metrics to quantify structural changes and the onset of crystallisation in random sphere packs. Here we specifically discuss the expectation values of these metrics for simple crystalline unimodal packings of spheres, consisting of single spheres on the points of a Bravais lattice. These data provide an important reference for the discussion of anisotropy values of disordered structures that are typically of relevance in granular systems. This analysis demonstrates that, at least for sufficiently high packing fractions above φ > 0.61, crystalline sphere packs exist whose Voronoi cells are more anisotropic with respect to a volumetric moment tensor than the average value of Voronoi cell anisotropy in random sphere packs.
|Publication Type:||Conference Paper|
|Copyright:||© 2013 AIP Publishing LLC|
|Notes:||AIP Conference Proceedings|
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