Surface-state hole decay mechanisms: The Be(0001) surface

First-principle calculations and angle-resolved photoemission experiments are combined to analyze the different contributions to the surface-state hole dynamics at the Be(0001) surface. The computed inelastic electron-electron scattering rate γ is in good agreement with experiment once the electron-phonon contribution is subtracted. {γ} is strongly influenced by details of the surface band structure. In particular, the intraband transitions within the surface state itself ignored in traditional Fermi liquid theory contribute 65%-85% to {γ}. This intraband contribution and the highly spatial nonlocality of the self-energy makes the energy and momentum dependence of {γ} to be ∝(EF-E)^α (with {α}2) in contrast to the observed {α}{}2 value in noble and transition metal surfaces.