Electronic structure and bonding in skutterudite-type phosphides

The electronic structures of the skutterudite-type phosphides CoP3 and NiP3 have been investigated by means of first-principles linear muffin-tin orbital-atomic sphere approximation band-structure calculations. The presence of P-4 rings in the skutterudite structure is of great importance in determining the nature of the electronic bands around the Fermi level, composed mainly of pi-type molecular orbitals of these units. The metallic character found for NiP3 should be ascribed to the phosphorus framework rather than to the metal atoms.