Crystals with sublattices belonging to the cubic system and special features of their elementary excitation spectra

Genesis of spectra of elementary excitations of crystals comprising sublattices belonging to the cubic system is investigated. Using the methods of group theory, the Brillouin sublattice zones are transformed into the Brillouin crystal zones, and degeneration is established caused by the convolution of branches of the spectrum. The degeneration is removed with allowance for hybridization of sublattice states. The special features of the band spectra of some crystals belonging to the cubic system are discussed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 21–27, May, 2006.