Band widening in graphite

Abstract

The valence band width of graphite is determined with high accuracy by imaging the momentum distribution of photoelectrons for various binding energies. Compared to local-density-functional theory, the experimental band width (22.0 eV) is stretched by about 11%. Quasiparticle calculations, which properly describe electron interaction effects on the excited states of a solid, give a width of 21.8 eV, in agreement with the experiment within the experimental and theoretical relative uncertainty of about 1%. The results demonstrate the importance of including final-state and associated many-body effects into the theoretical description of the electronic structure of solids.