Lowest-energy site for hydrogen in diamond

We investigate the locations, electronic energy levels and motion of hydrogen in diamond with tight-binding total energy calculations and Molecular Dynamics simulations. A lowest energy site for hydrogen in diamond is found. It is a sixfold degenerate site (with respect to the C-C bond), giving rise to a dangling bond and to a deep electronic level in the energy gap. The motion of the hydrogen atom in the diamond crystal is jumplike between these stable sites, starting at above similar to 400 K. It is a coupled-barrier diffusion, with an activation energy of 0.9 eV.