Density-functional theory for plutonium

We review developments in the theoretical description and understanding of plutonium in terms of a metal with itinerant (band) 5f electrons. Within this picture most facets of this remarkable and anomalous material are accurately described by first-principle, parameter-free, density-functional-theory (DFT) calculations. We show that the model explains plutonium's phase stability, elasticity, lattice vibrations, electronic structure, alloy properties, and magnetism. Fluctuations are addressed by means of constrained DFT calculations and new light is shed on the anomalous properties of delta plutonium, including explaining its negative thermal expansion. Effects of alloying and point defects in plutonium are also addressed. It is further emphasized that strong electron correlations, originating from a large intra-atomic Coulomb repulsion (similar to 4 eV) of the 5f electrons, that has often been assumed for plutonium in the literature, is inconsistent with the experimental phase diagram of plutonium.