The linewidth of surface states of simple metals

The linewidths (inverse lifetimes) Gamma(e-e) of Be(0001) and Mg(0001) surf ace electronic states are calculated as the projection of the imaginary par t of the self-energy operator of a quasiparticle onto the state. The screen ed Coulomb interaction is calculated using a model potential, which takes i nto account the energy gap in the band structure and a surface state locate d in this gap. The wave functions and energies of electron states are calcu lated by a self-consistent film pseudopotential method. It is shown that Ga mma(e-e) essentially depends on the position of the surface state in the Br illouin zone. The difference between the calculated values of Gamma(e-e) an d those obtained in a homogeneous electron gas model is shown to be basical ly due to transitions from surface bands. (C) 2000 MAIK "Nauka/Interperiodi ca".