부산대학교 도서관

A model of the energy band structure of iron borate (FeBO[sub 3]) is proposed that combines a one-electron description of the sp states of boron and oxygen with a many-electron description of the d states of iron. The Green functions of d electrons are calculated using the exact Lehmann spectral representation. The energies of the d-type quasiparticles are calculated using terms of the d [sup 4] ,d [sup 5] , and d [sup 6] electron configurations. The optical absorption spectrum of FeBO[sub 3] is determined by local excitons and by the electron excitations with charge transfer. The latter excitations control the nature of the dielectric gap in FeBO[sub 3] crystals. The model parameters are determined from a comparison to the exciton energies. The density of single-particle states in FeBO[sub 3] is calculated. The main bands in the calculated optical absorption spectrum agree well with experimental data for energies up to 3 eV. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]