Spectral properties of δ -plutonium: Sensitivity to 5f occupancy

By combining the local density approximation (LDA) with dynamical mean field theory (DMFT), we report a systematic analysis of the spectral properties of δ -plutonium with varying 5f occupancy. The LDA Hamiltonian is extracted from a tight-binding fit to full-potential linearized augmented plane-wave calculations. The DMFT equations are solved by the exact quantum Monte Carlo (QMC) method and by the Hubbard-I approximation. We demonstrate strong sensitivity of the spectral properties to the 5f occupancy, which suggests using this occupancy as a fitting parameter in addition to the Hubbard U. By comparing with photoemission data, we conclude that the "open shell" 5 f5 configuration gives the best agreement, resolving the controversy over 5f "open shell" versus "close shell" atomic configurations in δ-Pu.