Abstract
Quasi-self-consistent relativistic energy band structures are reported for the stoichiometric actinide monocarbides (ThC, PaC, UC and NpC). Three computational procedures used in this work (muffin-tin partitioning of space, the Xalpha approximation and self consistency) are examined critically for PaC. The computed band structures, although superficially similar, show marked differences-the major trends across the series are the dramatic increase in f-electron participation in the bonding, the change in character of the Fermi energy from d to f at PaC and the increasing localisation and concomitant narrowing of the f-electron bands. It is concluded that at ThC 5f electron participation in the bonding is minimal, but that this contribution is important for PaC and the later members of the actinides.