A multi-scale study was made of hydrogen clustering at the surface of (10,0) carbon nanotubes. A systematic study of the binding energies and migration barriers of hydrogen adatoms and various close adatom pairs was undertaken using density-functional theory. The interaction between hydrogen atoms on the surface of nanotubes was shown to be long-ranged and anisotropic. Upon applying the obtained potential energy surfaces for lattice kinetic Monte Carlo simulations of chemisorbed hydrogen annealing, a noticeable effect of the annealing conditions upon cluster sizes, shapes and relative populations was revealed. Multiscale Study of Hydrogen Diffusion and Clustering on Carbon Nanotube. T.T.Vehvilainen, M.G.Ganchenkova, V.A.Borodin, R.M.Nieminen: Journal of Nanoscience and Nanotechnology, 2009, 9[7], 4246-53