Role of the plasmon-pole model in the GW approximation.

Band gaps and band-edge energy levels are computed using the many-body perturbation theory within the GW approximation, with four common plasmon pole models (PPMs) and numerical integration employed to evaluate the dynamic screening matrix. Although the Hybertsen-Louie PPM is often adopted in GW calculations because it predicts band gaps best matching experimental data, we show that it is the Godby-Needs construction that agrees consistently with numerical integration on dynamic screening for materials with distinct characteristics. The variation in predicted band gaps due to different PPMs used can be as large as 1 eV in strongly localized electronic systems, and the band-edge energy levels are more sensitive to the choice of PPM than band gap even in simple semiconductors. [ABSTRACT FROM AUTHOR]