  We investigate the structure and equilibrium linear-response dynamics of
suspensions of hard colloidal dumbbells using Brownian Dynamics computer
simulations. The focus lies on the dense fluid and plastic crystal states of
the colloids with investigated aspect (elongation-to-diameter) ratios varying
from the hard sphere limit up to 0.39, which is roughly the stability limit of
the plastic crystal phase. We find expected structural changes with larger
elongation with respect to the hard sphere reference case and very localized
orientational correlations, typically just involving next-neighbor couplings.
These relatively weak correlations are also reflected in only minor effects on
the translational and rotational diffusion coefficients for most of the
investigated elongations. However, the linear response shear viscosity exhibits
a dramatic increase at high packing fractions ($\phi\gtrsim 0.5$) beyond a
critical anisotropy factor of about $L^* \simeq 0.15$ which is surprising in
view of the relatively weak changes found before on the level of colloidal
self-dynamics. We suspect that even for the small investigated anisotropies,
newly occurring, collective rotational-translational couplings must be made
responsible for the slow time scales appearing in the plastic crystal.
