Electronic energy bands in β-cerium

Abstract

Electronic-energy-band calculation has been done by the Korringa-Kohn-Rostoker (KKR) method for β-cerium with the Kohn-Sham-Gaspar (KSG) exchange term in the crystal potential. The energy eigenvalues have been calculated at 57 points uniformly distributed over three symmetry planes in the Brillouin zone. They have also been obtained in fair detail along a few major symmetry directions. The electronic states have been classified using the symmetrized-augmented-plane-wave method, as achieving this by KKR method requires much more computational effort. It is found that the f band in β-cerium lies above the Fermi level, and the s-d complex shows good qualitative agreement with the band pattern in α-lanthanum. The density of states at the Fermi level has been found to be 1.71 (e/at.)/eV. However, it appears that the conventional band picture may not describe the f level in metallic cerium very accurately. Within its limitation, the band-structure calculation, where strong correlations are not involved, explains the situation in cerium better when we use KSG exchange rather than Slater exchange. It is suggested that x-ray absorption experiments should be done to check if the f band lies above the Fermi level as found in this calculation.