Surface-state hole decay mechanisms: The Be(0001) surface - art. no. 085334

First-principle calculations and angle-resolved photoemission experiments a re combined to analyze the different contributions to the surface-state hol e dynamics at the Be(0001) surface. The computed inelastic electron-electro n scattering rate gamma is in good agreement with experiment once the elect ron-phonon contribution is subtracted. gamma is strongly influenced by deta ils 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 gamma. This intraband contribution and the highly sp atial nonlocality of the self-energy makes the energy and momentum dependen ce of gamma to be proportional to (E-F-E)(alpha) (with alpha <2) in contras t to the observed <alpha>similar or equal to2 value in noble and transition metal surfaces.