  We report on theoretical and numerical study of propagation of atomic beams
crossing a detuned standing-wave laser beam in the geometric optics limit. The
interplay between external and internal atomic degrees of freedom is used to
manipulate the atomic motion along the optical axis by light. By adjusting the
atom-laser detuning, we demonstrate how to focus, split and scatter atomic
beams in a real experiment. The novel effect of chaotic scattering of atoms at
a regular near-resonant standing wave is found numerically and explained
qualitatively. Some applications of the effects found are discussed.
