Density Fluctuations and Hyperuniformity in Dense Packings of Superballs, Charles Maher, G4 (3959561)
A packing is any collection of nonoverlapping objects. Dense, disordered packings are useful models of glasses, biological systems, and granular media. The study of dense packings of nonspherical particles enables one to ascertain how rotational degrees of freedom affect the properties of packings. Here, we study superballs, a large family of deformations of the sphere, each of which is characterized by a deformation parameter p>0 which indicates to what extent the shape deviates from a sphere. As p increases from the sphere point (p=1), the superball becomes cube-like, and becomes octahedron-like when p<1. We generate disordered superball packings with a wide range of values of p both greater than and less than 1. We characterize their density fluctuations using the spectral density and find that on large length scales the density fluctuations are smaller than those in a typical disordered system, meaning they are "hyperuniform". Hyperuniform systems are known to have desirable physical properties, e.g., excellent electrical or thermal conductivity. This result can be used to help inform the design of hyperuniform granular materials.