Local field corrections in two-dimensional coupled electron–LO phonon systems

Abstract

We theoretically investigate the effects of vertex corrections on the many-body properties of a two-dimensional electron gas system in which the electrons are coupled to the LO phonons under adiabatic conditions. We calculate the vertex-corrected electron self-energy, spectral function, damping rate, lifetime and inelastic mean free path in a coupled electron–LO phonon system at zero temperature. Because of the adiabatic situation, we neglect the phonon vertex correction in our calculations. We go beyond the random phase approximation (RPA) and consider the short-range exchange and correlation interactions by using the Hubbard and Singwi–Tosi–Land–Sjölander (STLS) approximations. In general, our results show that by decreasing the electron density, the vertex effects become more significant and the STLS approximation has a stronger effect than does the Hubbard approximation. We find that including the vertex corrections yields sharper quasiparticle peaks compared with the RPA approach. In addition, longer quasiparticle lifetimes and mean free paths are obtained when the vertex corrections are taken into account.