▎ 摘　　要

With density functional theory calculations, the performance of hydrogen trimers on graphene including the structural stability and the dynamical evolution paths is systematically investigated. The stability of the trimer is closely related with its adsorption configuration. The configurations containing ortho-dimers and para-dimers are more stable than the others. Meanwhile, other nearby hydrogen clusters have different impacts on the stability of trimers, which is determined by the competition between lattice deformation and inter-cluster electronic pairing. Atomic diffusion and desorption are proved to be very important for the dynamical evolution paths of trimers, in which all trimers are first easily changed into stable dimers and then follow the desorption of dimers. Our results have well explained the phenomena given by the scanning tunneling microscopy experiments and are helpful for the understanding of the interaction between hydrogen and graphene, and for the application of hydrogenated graphene. (C) 2013 AIP Publishing LLC.