  Ab initio molecular dynamics calculations of deuterium desorbing from Si(100)
have been performed in order to monitor the energy redistribution among the
hydrogen and silicon degrees of freedom during the desorption process. The
calculations show that part of the potential energy at the transition state to
desorption is transferred to the silicon lattice. The deuterium molecules leave
the surface vibrationally hot and rotationally cold, in agreement with
experiments; the mean kinetic energy, however, is larger than found in
experiments.
