  We study the formation of bands of colloidal particles driven by periodic
external fields. Using Brownian dynamics, we determine the dependence of the
band width on the strength of the particle interactions and on the intensity
and periodicity of the field. We also investigate the switching (field-on)
dynamics and the relaxation times as a function of the system parameters. The
observed scaling relations were analyzed using a simple dynamic
density-functional theory of fluids.
