Self-consistent electronic structure of a transition-metal surface with an adsorbate: H on Mo(001)

The self-consistent pseudopotential method is applied to calculate the electronic structure of an ideal Mo(001) surface which is covered by a saturated monolayer of hydrogen. The calculation is performed for two values of $d$, the hydrogen-substrate interlayer distance. For $d=0.75\mathrm{}$ Å, the work function is identical to the experimental value of 4.9 eV. For $d=0\mathrm{}$, the work function is shown to be smaller by 50%. The effect of saturated hydrogen chemisorption on the electronic structure of the surface results in two adsorbate-induced bands which lie below the substrate bulk bands. Most of the intrinsic surface states of the clean substrate continue to exist at the hydrogen-covered surface but at slightly lower energies. Recent angular-resolved photoemission data give some support to these results.