The joint densities of states of LaB6 were calculated by using a band structure with different 4f-level positions and compared with the optical conductivity spectrum (σ(ω)) due to the interband transition from 2 to 22eV. The purpose was to confirm a previous assignment of the origin of the peaks resolved in (σ(ω)) and to check whether the band model was applicable to the present systems. It was found that peaks at 7 and 9eV in (σ(ω)) were due to a transition from B-2p to La-5d and that at 3.5eV in (σ(ω)) was due to a transition between B-2p bonding and antibonding states and its exciton.

Comparison between Optical Conductivity Spectrum and Band Structure in LaB6. Kimura, S.I., Harima, H., Nanba, T., Kunii, S., Kasuya, T.: Journal of the Physical Society of Japan, 1991, 60[3], 745-8