Specific features of the electronic structure and spectral characteristics of the Gd$_{5}$Si$_{3}$

The electronic structure and optical properties of the hexagonal intermetallic compound Gd$_{5}$Si$_{3}$ are investigated. The spin-polarization calculation of the band spectrum is performed in the local spin density approximation, taking account for the strong electron correlations in the 4$f$ shell of a Gd ion (LSDA + U method). Optical constants of the compound in the wavelength range of 0.22–15 $\mu$m are determined by the ellipsometry technique and some spectral characteristics are calculated. The frequency dependence of optical conductivity in the light quantum absorption region is analyzed on the basis of the calculated electron density of states.