Surface relaxation and electronic structure of Mo and W (100)

The influence of the uniform surface contraction, observed at room temperature for Mo and W (100), on their electronic structure, is investigated and discussed in a tight-binding framework. Unexpectedly, the central resonant peak of the surface density of states is only slightly modified and the contraction results mainly in an increase of the density of states near the band edges. Introducing the core-core repulsion with a phenomenological potential, the minimization of energy gives a 6 ∼ 8 % and 3.5 ∼ 4 % contraction for Mo and W respectively, in good agreement with experiment.