Extended Hückel Molecular Orbital (EHMO) theory has been applied to the problem of hydrogen atom site location in titanium clusters Ti4, Ti5, Ti17 and Ti20, the latter simulating the hcp metal face (0001). In agreement with previous ab initio calculations, it is found that an external position for the hydrogen atom over a three-fold coordination site is favored over all internal positions in a perfect crystal. Among the internal positions, tetrahedral sites are favored over octahedral ones. The binding energies of internal sites appear to be e...
