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 $\sim 400\hspace{0.5em}\mathrm{K}.$ It is a coupled-barrier diffusion, with an activation energy of 0.9 eV.