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 P4 rings in the skutterudite structure is of great importance in determining the nature of the
electronic bands around the Fermi level, composed mainly of p-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