We study chemical reaction between a single hydrogen atom and a graphene,
which is the elemental reaction between hydrogen and graphitic carbon
materials. In the present work, classical molecular dynamics simulation is used
with modified Brenner's empirical bond order potential. The three reactions,
that is, absorption reaction, reflection reaction and penetration reaction, are
observed in our simulation. Reaction rates depend on the incident energy of the
hydrogen atom and the graphene temperature. The dependence can be explained by
the following mechanisms: (1) The hydrogen atom receives repulsive force by
pi-electrons in addition to nuclear repulsion. (2) Absorbing the hydrogen atom,
the graphene transforms its structure to the ``overhang'' configuration such as
sp-3 state. (3) The hexagonal hole of the graphene is expanded during the
penetration of the hydrogen atom.Comment: 10 pages, 9 figures. This paper was submitted to PR
