We present results of wavepacket simulations of scattering of an oriented
methane molecule from a flat surface including all nine internal vibrations. At
a translational energy up to 96 kJ/mol we find that the scattering is almost
completely elastic. Vibrational excitations when the molecule hits the surface
and the corresponding deformation depend on generic features of the potential
energy surface. In particular, our simulation indicate that for methane to
dissociate the interaction of the molecule with the surface should lead to an
elongated equilibrium C--H bond length close to the surface.Comment: RevTeX 15 pages, 3 eps figures: This article may be found at
http://link.aip.org/link/?jcp/109/1966