Electronic structure of cerium: A comprehensive first-principles study

Cerium, in which the 4f valence electrons live on the brink between localized and itinerant characters, exhibits varying crystal structures and therefore anomalous physical properties with respect to temperature and pressure. Understanding its electronic structure and related lattice properties is one of the central topics in condensed matter theory. In the present paper, we employed the state-of-the-art first-principles many-body approach (i.e., the density functional theory in combination with the single-site dynamical mean-field theory) to thoroughly study its electronic structure. The momentum-resolved spectral functions, total and 4f partial density of states, optical conductivities, self-energy functions, and atomic eigenstate histograms for cerium's four allotropes under ambient pressure were calculated and analyzed carefully. The calculated results demonstrate that the 4f electrons in the alpha, beta, gamma, and delta phases are all correlated with heavily renormalized electron masses. In the alpha phase, the 4f electrons tend to be itinerant, which causes strong hybridization between the 4f and spd bands and a remarkable 4f valence state fluctuation, while for the other phases, the 4f electrons are close to being localized. Our calculated results support the Kondo volume collapse scenario for the cerium alpha-gamma transition. Finally, we examined the site dependence of the 4f electronic structure in the beta phase. The calculated results suggest that it does not exhibit a site-selective 4f localized state.