OPTICAL PROPERTIES OF BiSeI CRYSTALS.

Task of this work is theoretical and experimental investigation of the optical properties and optical transitions in BiSel crystals in antiferroelectric phase (T = 295K). In the current paper we have calculated (DFT) and measured (optical reflectance ellipsometry) the dielectrics constants spectra of BiSel crystals. The theoretical and experimental imaginary dielectric constants were compared. Experimental spectra of the constants were analyzed considering that spectra structure consists of four Laurence lines sum. The Laurence line parameters are obtained by minimization using the mean-square method of the difference between the calculated and measured spectra of the dielectric constants. [ABSTRACT FROM AUTHOR]