For our adsorption energy calculations, hydrogen atoms were added to a given surface adsorption site and allowed to relax normal to the surface. We constructed low coverage structures that have hydrogen atoms adsorbed at isolated sites and as dimers with two atoms occupying neighboring sites. High coverage structures have all surface sites filled and variations with single site or double site vacancies. As possible sets of intermediate structures, we filled all sites of one type and included variations with single or double vacancies as well as single or double occupancy of the other site type.