Band Dispersion of Localized Valence States in LiF(100)

The band dispersion of the localized, F 2p-like valence band of LiF is mapped using an imaging technique to obtain k(E). The bandwidth is 3.5 eV (from Γ₁₅ to X₄^'). This is 17% wider than predicted by first-principles band calculations, implying an expansion of the bandwidth by self-energy effects in qualitative agreement with quasiparticle calculations. The self-energy effect is opposite to that seen in delocalized systems, such as alkali metals.