An AIMD+U simulation of low-energy displacement events in UO2

Abstract

In UO2, due to the existence of U 5f electrons, the strong-correlation effects are significant, and correction of on-site Coulomb interaction is necessary. For strongly-correlated electronic system like UO2, however, it is a challenge to consider such correction during simulation of their dynamic processes under radiation. In this study, a new method, i.e., AIMD + U, in which ab initio molecular dynamics method and correction of on-site Coulomb interaction between U 5f electrons are combined, is employed to investigate the response of UO2 to low energy radiation. The threshold displacement energies for O and U atoms have been determined, and defect creation and distribution have been provided. New mechanism for defect generation, and novel defect types, including uranium (oxygen) dumbbell interstitials and uranium antisite defects, are revealed from this study.