Quantifying the importance of orbital over spin correlations in $\delta$-Pu within density-functional theory
Per S\"{o}derlind

Spin and orbital 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 with this approach\cite{soderlind01,soderlind04} has included condensed-matter generalizations of Hund's three rules for atoms, i.e, spin polarization, orbital polarization, and spin-orbit coupling. Here we 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 $\delta$-Pu. We 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.

© 2008 The American Physical Society.