Advances in first-principles modelling of point defects in UO₂: f electron correlations and the issue of local energy minima

Abstract

Over the last decade, a significant amount of work has been devoted to point defect behaviour in UO2 using approximations beyond density functional theory (DFT), in particular DFT + U and hybrid functionals for correlated electrons. We review the results of these studies from calculations of bulk UO2 properties to the more recent determination of activation energies for self-diffusion in UO2, as well as a comparison with their experimental counterparts. We also discuss the efficiency of the three known methods developed to circumvent the presence of metastable states, namely occupation matrix control, U-ramping and quasi-annealing.