Optical absorption spectra of semiconductors and insulators including electron-hole correlations: An ab initio study within the LAPW method

The solution of the Bethe-Salpeter equation (BSE) for the electron-hole two-particle Green’s function has proven to yield optical absorption spectra of semiconductors and insulators beyond the independent quasiparticle approximation. The inclusion of electron-hole correlations greatly improves the accordance with experimental data. In this work we present an implementation of the BSE scheme into the linearized augmented plane-wave method, and apply our method to the semiconductor Si and to the wide band-gap insulator LiF. We discuss the effects of the electron-hole correlations and compare our results to the experimental data as well as to the previous theoretical findings.