Structural properties of dense hard sphere packings
  The structural properties of dense random packings of identical hard spheres (HS) are investigated. The bond order parameter method is used to obtain detailed information on the local structural properties of the system for different packing fractions $\phi$, in the range between $\phi=0.53$ and $\phi=0.72$. A new order parameter, based on the cumulative properties of spheres distribution over the rotational invariant $w_6$, is proposed to characterize crystallization of randomly packed HS systems. It is shown that an increase in the packing fraction of the crystallized HS system first results in the transformation of the individual crystalline clusters into the global three-dimensional crystalline structure, which, upon further densification, transforms into alternating planar layers formed by different lattice types. 
B.A. Klumov and S.A. Khrapak and G.E. Morfill
cond-mat.soft