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arXiv · 0904.1558

Excitations of Ellipsoid Packings near Jamming

Z. Zeravcic·N. Xu·A. J. Liu·S. R. Nagel·W. van Saarloos
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Abstract

We study the vibrational modes of three-dimensional jammed packings of soft ellipsoids of revolution as a function of particle aspect ratio $ε$ and packing fraction. At the jamming transition for ellipsoids, as distinct from the idealized case using spheres where $ε= 1$, there are many unconstrained and non-trivial rotational degrees of freedom. These constitute a set of zero-frequency modes that are gradually mobilized into a new rotational band as $|ε- 1|$ increases. Quite surprisingly, as this new band is separated from zero frequency by a gap, and lies below the onset frequency for translational vibrations, $ω^*$, the presence of these new degrees of freedom leaves unaltered the basic scenario that the translational spectrum is determined only by the average contact number. Indeed, $ω^*$ depends solely on coordination as it does for compressed packings of spheres. We also discuss the regime of large $|ε- 1|$, where the two bands merge.

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Z. Zeravcic, N. Xu, A. J. Liu, S. R. Nagel, W. van Saarloos. 2009-06-04. Excitations of Ellipsoid Packings near Jamming. https://doi.org/10.1209/0295-5075%2F87%2F26001

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