  The collective motion of dust particles during the mode-coupling induced
melting of a two-dimensional plasma crystal is explored in molecular dynamics
simulations. The crystal is compressed horizontally by an anisotropic
confinement. This compression leads to an asymmetric triggering of the
mode-coupling instability which is accompanied by alternating chains of
in-phase and anti-phase oscillating particles. A new order parameter is
proposed to quantify the synchronization with respect to different directions
of the crystal. Depending on the orientation of the confinement anisotropy,
mode-coupling instability and synchronized motion are observed in one or two
directions. Notably, the synchronization is found to be direction-dependent.
The good agreement with experiments suggests that the confinement anisotropy
can be used to explain the observed synchronization process.
