  The possible occurrence of either a charge-density-wave or a Kohn anomaly is
governed by the presence of Fermi-surface nesting and the subtle interaction of
electrons and phonons. Recent experimental and theoretical investigations
suggest such an effect for the hydrogen covered Mo and W(110) surfaces. Using
density-functional theory we examine the electronic structure and the
electron-phonon coupling of these systems. Besides good agreement with the
experimental phonon frequencies our study provides a characterization and
quantitative analysis of an unusual scenario determining the electronic,
vibrational, and structural properties of these surfaces.
