ELECTRONIC-STRUCTURE OF THE LIMGH3 CLASS OF COMPOUNDS - CLUSTER CALCULATIONS

The lattice spacing and the electronic structure of LiMgH3, NaMgH3, and LiCaH3 have been calculated by modeling these hydrides as clusters with modified perovskite structure and using the self-consistent-field linear-combination-of-atomic-orbitals molecular-orbitals theory. This yields lattice constants of 3.47, 3.53, and 4.07 angstrom for LiMgH3, NaMgH3, and LiCaH3, respectively. The electronic structure of LiMgH3 is characteristic of an insulating material. The gap at the Fermi energy in the density of states of LiMgH3 is, however, significantly less than that of LiBeH3 and is insensitive to moderate changes in the interatomic spacing. On the other hand, LiCaH3 and NaMgH3 are both found to exhibit metallic character with the Fermi energy lying in regions of high electron density of states.