Electronic energy bands have been calculated for Ce${\mathrm{H}}_2$ and Ce${\mathrm{H}}_3$ using the augmented-plane-wave method and have been fitted by the linear-combination-of-atomic-orbitals interpolation scheme. The partial densities of states and the numbers of electrons on atomic orbitals indicate that hydrogen in Ce${\mathrm{H}}_2$ is almost anionlike. When going from Ce${\mathrm{H}}_2$ to Ce${\mathrm{H}}_3$, shallow bonding levels are found to form between the third hydrogen state and conduction electrons of Ce${\mathrm{H}}_2$, other features of Ce${\mathrm{H}}_2$ being little affected by it. Thus the rare-earth dihydrides are regarded as ionic compounds similar to the saline-element dihydrides except for the presence of $d$-like conduction electrons.

• Received 27 March 1980

DOI:https://doi.org/10.1103/PhysRevB.22.3573