  We comprehensively study mechanical and vibrational properties of dimer
packings in three-dimensional space with particular attention on critical
scaling behaviors near the jamming transition. First, we confirm the dependence
of the packing fraction at the transition on the aspect ratio, the isostatic
contact number at the transition, and the scaling dependence of the excess
contact number on the excess density. Second, we study the elastic moduli, bulk
and shear moduli, and establish power-law scaling of them. Finally, we study
the vibrational density of states and its characteristic frequency. The
vibrational density of states shows two plateaus in the lower- and
higher-frequency regions, which are characterized by rotational and
translational vibrational modes, respectively. The onset frequency of the
lower-frequency plateau scales linearly to the square root of excess density.
The scaling laws in the mechanical and vibrational properties are consistent
between two- and three-dimensional dimers, and they are identical to those in
spheres.
