Site and nature of H bonding on Ti (0001)

The site and nature of the bonding of H at a Ti (0001) surface are established via the analysis of new angle-resolved photoemission measurements by self-consistent electronic-structure calculations. Experimentally observed H-induced surface states are identified with calculated bonding and antibonding combinations of H $1s$ and Ti $3d$, $4s$ orbitals. The positions of these levels are strongly dependent on local bonding geometry. The H site which minimizes the total energy gives a very good account of the observed spectrum. Ignoring the total energy leads to a more ambiguous structure determination.