  The smearing of the graphene/graphane interface due to the thermally
activated migration of hydrogen atoms is studied by the molecular dynamics
method. Contrary to expectations, it is found that the fast spontaneous
regeneration of this interface occurs even at a sufficiently high temperature T
about 1500 K. As a result, the average width of the disordered region does not
exceed the length of a C-C bond, i.e., the interface remains almost atomically
sharp. The cause of this effect appears to be the specific shape of the
potential relief of the system, namely, the significant difference between the
heights of the energy barriers for the direct and inverse migrations of
hydrogen atoms. A simple model that makes it possible to obtain the temperature
dependence of the equilibrium distribution function of typical atomic
configurations, to estimate the typical time of establishing the equilibrium
state, and thereby to quantitatively describe the results of the computer
experiment is presented.
