  A semiclassical model is used to investigate oscillations of atomic fermions
in a combined magnetic trap and one dimensional optical lattice potential
following axial displacement of the trap. The oscillations are shown to have a
characteristic small amplitude, damped behavior in the collisionless regime.
The presence of a separatrix in the semiclassical Brillouin zone phase space is
predicted and shown to produce a strongly asymmetric phase space distribution
function.
