Influence of unoccupied5f-band states on the Fermi surface of Th metal

The influence of unoccupied $5f$-band states on the Fermi surface of Th metal is determined by means of highly precise calculations of the Fermi-surface areas and effective masses. Comparison with experiment shows excellent agreement when the $5f$ electrons are treated as itinerant, unlike the predictions of the localized ($f$ states removed) model. This result adds strong evidence for the itinerant nature of the occupied $5f$ states in the light actinides.