  Six-dimensional quantum dynamical calculations of the scattering of H_2 from
a Pd(100) surface using a potential energy surface derived from
density-functional theory calculations are presented. Due to the corrugation
and anisotropy of the PES strong off-specular and rotationally inelastic
diffraction is found. The dependence of the diffraction intensitities on the
incident kinetic energy is closely examined. In particular we focus on the
quantum oscillations for normal and off-normal incidence.
