Novel electronic configuration in δ - Pu

We present evidence for a unique electronic configuration, which we call the mixed-level state, that is consistent with most of the anomalous properties of partial derivative-Pu. The unique properties of this state result from a subdivision of the 5f manifold into orthogonal sub-sets, one with localized character, contributing atomic-like correlation to the total energy, and the other of itinerant character, contributing 5f-electron bonding to the total energy. The near-degeneracy of alpha- and delta-phases of Pu and the unusual equilibrium volume, elastic constants, and thermal expansion of delta-phase are consistent with this configuration. (C) 1999 Elsevier Science S.A. All rights reserved.