Optical properties and electronic structure of mercury iodide

The spectra of sets of optical functions of a HgI$_2$ crystal for the polarization $\mathbf{E}\perp\mathbf{c}$ are determined in the energy range of 0–20 eV. The $\varepsilon_2$ and -Im$\varepsilon^{-1}$ spectra are decomposed into elementary components with establishment of their principal parameters. The calculations are carried out based on the experimental reflection spectrum at 100 K for $\mathbf{E}\perp\mathbf{c}$ and computer programs composed with the help of integral Kramers–Kronig relations, analytical formulas, and the method of combined Argand diagrams. The principal features of the $\varepsilon_2$ and -Im$\varepsilon^{-1}$ spectra of optical functions and parameters of components of the decomposition bands are established.