Quasiparticle band structure

Many body effects influence the energy-versus-momentum relation that is measured in angle resolved photoemission experiments and the quasiparticle band structure may be significantly different from what is deduced within the independent particle model. In the case of cobalt many body effects are even more drastic than an energy renormalization giving rise to a quenching of quasiparticle peaks. Augmenting ab-initio band structure with many-body e-e interactions we have obtained spin- and k-dependent self-energies, hole spectral functions and quasiparticle energies to be compared with photoemission spectra; our results show that e-e correlations are responsible for strong spin-dependent energy renormalizations.