Electronic structure and optical properties of rare earth hexaborides RB₆ (R = La, Ce, Pr, Nd, Sm, Eu, Gd)

The optical and electronic properties of the rare earth hexaborides RB ₆ (R = La, Ce, Pr, Nd, Sm, Eu, Gd) are studied using the full potential linearized augmented plane wave method. To account better for the on-site f-electron correlation, we adopted the Coulomb corrected local spin density approximation (LSDA+U) to the exchange correlation functional in the calculations. Our electronic structure calculation shows the overlapping of R5d states and B2p states at the X symmetry point. The magnetic moment of the ferromagnetic rare earth hexaborides increases with increasing 4f occupation. The calculated reflectivity and optical conductivity spectra are in agreement with the experimental data, although the structures in the calculated optical spectra are sharper.