Simulations of low energy cascades in fcc Pu metal at 300 K and constant volume

Recently progress has been achieved with a modified embedded atom method (MEAM) potential for pure Pu. The MEAM potential is able to capture the most salient features of atomic volume and enthalpy of solid and liquid Pu metal as a function of temperature at zero pressure. The atomic volume difference between monoclinic (α-phase) and fcc (δ-phase) was captured nearly quantitatively. From molecular dynamics (MD) simulations, we find that Pu, under these conditions, has an approximately 10 eV minimum displacement threshold energy, very low compared to most other fcc metals, and shows less crystallographic anisotropy in this minimum. At 0 K, the constant volume cell relaxes to a rhombohedrally distorted structure, which is connected to the low minimum displacement threshold energy. Split interstitials orient themselves in a 〈100〉 direction and migrate over a 0.056 eV barrier. Mono-vacancies migrate over a 0.84-1.00 eV barrier.