Relativistic calculations of 2p and 3d excitation energies in the actinide metals.

Abstract

A systematic investigation of 2p and 3d core-electron excitation energies in the actinide metals Ac--Am is described. Crystal potentials are constructed via the renormalized-atom method, and excitation energies are derived from differences between band total energies for various fixed, integral values of the 5f occupancy n. Calculations have been performed for the principal excitations, involving 6d-7s conduction-electron screening of a core hole, as well as for levels associated with 5f screening in the final state. For a given metal the principal excitation energies decrease at a rate of 4--6 eV per increment in n, while the 5f-screened levels are less sensitive to 5f occupation. The energetics of 6d-7s versus 5f screening is examined by calculations for ionized final states. We compare our findings with analogous results for core levels in the rare earth metals and with recent experimental information.