  We show using numerical simulations that vortices in honeycomb pinning arrays
can exhibit a remarkable variety of dynamical phases that are distinct from
those found for triangular and square pinning arrays. In the honeycomb arrays,
it is possible for the interstitial vortices to form dimer or higher n-mer
states which have an additional orientational degree of freedom that can lead
to the formation of vortex molecular crystals. For filling fractions where
dimer states appear, a novel dynamical symmetry breaking can occur when the
dimers flow in one of two possible alignment directions. This leads to
transport in the direction transverse to the applied drive. We show that
dimerization produces distinct types of moving phases which depend on the
direction of the driving force with respect to the pinning lattice symmetry.
When the dimers are driven along certain directions, a reorientation of the
dimers can produce a jamming phenomenon which results in a strong enhancement
in the critical depinning force. The jamming can also cause unusual effects
such as an increase in the critical depinning force when the size of the
pinning sites is reduced.
