  We examine colloidal particles driven over a periodic muffin tin substrate
using numerical simulations. In the absence of a driving force this system
exhibits a rich variety of commensurate and incommensurate static phases in
which topological defects can form domain walls, ordered stripes,
superlattices, and disordered patchy regimes as a function of the filling
fraction. When an external drive is applied, these different static phases
generate distinct dynamical responses. At incommensurate fillings the flow
generally occurs in the form of localized pulses or solitons correlated with
the motion of the topological defect structures. We also find dynamic
transitions between different types of moving states that are associated with
changes in the velocity force curves, structural transitions in the topological
defect arrangements, and modifications of the velocity distributions and
particle trajectories. We find that the dynamic transitions between ordered and
disordered flows exhibit hysteresis, while in strongly disordered regimes there
is no hysteresis and the velocity force curves are smooth. When stripe patterns
are present, transport can occur along the stripe direction rather than along
the driving direction. Structural dynamic transitions can also occur within the
pinned regimes when the applied drive causes distortions of the interstitially
pinned particles while the particles trapped at pinning sites remain immobile.

Soft Condensed Matter