The development of embedded atom method (EAM) many-body
potentials for actinide oxides and associated mixed oxide (MOX) systems has
motivated the development of a complementary parameter set for gas-actinide and
gas-oxygen interactions. A comprehensive set of density functional theory (DFT)
calculations were used to study Xe and Kr incorporation at a number of sites in CeO2,
ThO2, UO2 and PuO2. These structures were used to fit a potential, which was used to
generate molecular dynamics (MD) configurations incorporating Xe and Kr at 300 K,
1500 K, 3000 K and 5000 K. Subsequent matching to the forces predicted by DFT for
these MD configurations was used to refine the potential set. This fitting approach
ensured weighted fitting to configurations that are thermodynamically significant
over a broad temperature range, while avoiding computationally expensive DFTMD
calculations. The resultant gas potentials were validated against DFT trapping
energies and are suitable for simulating combinations of Xe and Kr in solid solutions
of CeO2, ThO2, UO2 and PuO2, providing a powerful tool for the atomistic simulation
of conventional nuclear reactor fuel UO2 as well as advanced MOX fuels.