Exploring Metastable States in UO${}_2$ using Hybrid Functionals and Dynamical Mean Field Theory

Abstract

A detailed exploration of the $f$-atomic orbital occupancy space for UO${}_2$ is performed using a first principles approach based on density functional theory (DFT), employing a full hybrid functional within a systematic basis set. Specifically, the PBE0 functional is combined with an occupancy biasing scheme implemented in a wavelet-based algorithm which is adapted to large supercells. The results are compared with previous DFT+U calculations reported in the literature, while dynamical mean field theory (DMFT) is also performed to provide a further base for comparison. This work shows that the computational complexity of the energy landscape of a correlated $f$-electron oxide is much richer than has previously been demonstrated. The resulting calculations provide evidence of the existence of multiple previously unexplored metastable electronic states of UO${}_2$, including those with energies which are lower than previously reported ground states.

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Cited by in corpus (2)

• Electronic interaction $U_{pp}$ on oxygen $p$ orbitals in oxides: Role of correlated orbitals on the example of UO${}_2$ and TiO${}_2$
• First-principle Study of Multiple Metastable Charge Ordering States in La${}_{1/3}$Sr${}_{2/3}$FeO${}_3$