  We study Skyrmion dynamics in a (2+1)-dimensional Skyrme model. The system
contains a dimensionless parameter alpha, with alpha=0 corresponding to the
O(3) sigma-model. If two Skyrmions collide head-on, then they can either
coalesce or scatter -- this depends on alpha and on the incident speed v, and
is affected by transfer of energy to and from the internal vibrational modes of
the Skyrmions. We classify these internal modes and compute their spectrum, for
a range of values of alpha. In particular, we find that there is a fractal-like
structure of scattering windows, analogous to those seen for kink-antikink
scattering in 1+1 dimensions.
