  Hydrogen adsorption by graphite is examined by classical molecular dynamics
simulation using a modified Brenner REBO potential. Such interactions are
typical in chemical sputtering experiments, and knowledge of the fundamental
behavior of hydrogen and graphene in collisional conditions is essential for
modeling the sputtering mechanism. The hydrogen adsorption rate is found to be
dependent on the incident hydrogen energy and not on graphene temperature.
Rather than destroying the graphene, hydrogen incidence at energies of less
than 100 eV can be classified into three regimes of adsorption, reflection and
penetration through one or more graphene layers. Incidence at the lowest
energies is shown to distort the graphene structure.
