Hydrogen chemisorption on transition-metal surfaces: Tungsten (100)

A Hartree-Fock Green's-function theory of hydrogen chemisorption on transition-metal surfaces with a specific application to H on W(100) is presented. A complete set of basis wave functions, consisting of the $d$-wave functions of the metal substrate together with its continuum wave functions extending into the vacuum, is used, treating the $1s$ orbital of the adatom as an auxiliary orbital. The nonorthogonality of the basis wave functions with the $1s$ orbital is taken into account. The effect of the screening charge is considered phenomenologically in terms of an image potential. The binding energy, resonance levels seen in photo-and field emission, and the charge neutrality of the hydrogen atom for the W(100):H system are reasonably explained.