The gap in YH₃and its lattice structure

Abstract

A systematic study has been carried out on the electronic structure of YH3. The attention was focused on the conditions for finding an energy gap, in accordance with experimental evidence. The calculations are made with a localized spherical wave (LSW) program, which is based on a first-principles tight-binding version of the augmented spherical wave method. No gap was found for the FCC structure in spite of the use of a great variety of model parameters. However, a non-self-consistent run of the program for this structure reproduced the gap of 2 eV found by Switendick. No gap was found for several versions of the HCP structure either, including the rather complicated HoD3 structure. The separation of the bands around the Fermi level as found for the LaF3 structure, could explain the light transmission measurements.