On The Nature of the 5f States in Delta Plutonium

We present a theoretical model of the electronic structure of delta-Pu that is consistent with many of the electronic structure related properties of this complex metal. In particular we show that the theory is capable of reproducing the valence band photoelectron spectrum of delta-Pu. We report new experimental photoelectron spectra at several photon energies and present evidence that the electronic structure of delta-Pu is unique among the elements, involving a 5f shell with four 5f electrons in a localized multiplet, hybridizing with valence states, and approximately one 5f electron forming a completely delocalized band state.