Ab initio molecular dynamics simulations of overlapping recoil events in ThO2

Ab initio molecular dynamics is used to study defect production and interactions from overlapping atomic recoil events in thoria. The pre-existing defects, charge redistribution, and structural distortion from an initial recoil event significantly affect the dynamics of defect production processes that occur from a subsequent overlapping recoil event. The final defect configurations and increase in system energy are dependent on the incident directions and sequence of the recoils. A linear relationship between system potential energy and charge transfer at the distance of closest approach between the recoil and atomic nuclei demonstrates the important role of charge transfer in the response of thoria to single and overlapping recoils.