BAND-STRUCTURE AND METAL-TO-SEMICONDUCTOR TRANSITION IN THE CUBIC HYDRIDES OF 3B-SUBGROUP ELEMENTS

The band structures of Se, Y, La, and Ce dihydrides and La, Ce trihydrides were calculated by using the approximate KKR method. The results of our calculations are compared with APW calculations and experimental optical absorp ion and specific heat studies. The experimental situation for metal-to-semiconductor transitions in nonstoichiometric La and Ce trihydrides is discussed. In order to explain such transitions the model of an exitonic insulator is proposed.This model directly follows from our band structure calculations. © 1979, Akademische Verlagsgesellschaft.