Exchange and correlation effects in electronic excitations of Cu2O

State-of-the-art theoretical methods fail in describing the optical absorption spectrum, band gap, and optical onset of Cu2O. We have extended a recently proposed self-consistent quasiparticle approach, based on the GW approximation, to the calculation of optical spectra, including excitonic effects. The band structure compares favorably with our present angle-resolved photoemission measurements. The excitonic effects based on these realistic band structure and screening provide a reliable optical absorption spectrum, which allows for a revised interpretation of its main structures.