Quantifying the Importance of Orbital over Spin Correlations in Delta-Pu within Density-functional theory

摘要

Spin and orbital and electron correlations are known to be important when treating the high-temperature (delta) phase of plutonium within the framework of density-functional theory (DFT). One of the more successful attempts to model (delta)-Pu within this approach has included condensed-matter generalizations of Hund's three rules for atoms, i.e., spin polarization, orbital polarization, and spin-orbit coupling. Here they perform a quantitative analysis of these interactions relative rank for the bonding and electronic structure in (delta)-Pu within the DFT model. The result is somewhat surprising in that spin-orbit coupling and orbital polarization are far more important than spin polarization for a realistic description of (delta)-Pu. They show that these orbital correlations on their own, without any formation of magnetic spin moments, can account for the low atomic density of the (delta) phase with a reasonable equation-of-state. In addition, this unambiguously non-magnetic (NM) treatment produces a one-electron spectra with resonances close to the Fermi level consistent with experimental valence band photoemission spectra.