A plutonium α-decay defects production study through displacement cascade simulations with MEAM potential

This paper presents results of molecular dynamics simulations of self-irradiation in δ-Pu. The goal of this work is to understand, at an atomistic level, phenomena that lead to the experimentally observed swelling of plutonium-based materials. In a first step, we have performed a parametric study including both potential formalism, simulation cell size, temperature and cascade energy. The comparison of the EAM (Embedded Atom Method) and the MEAM (Modified Embedded Atom Method) shows that the behavior of displacement cascades in δ-Pu is strongly sensitive to the interaction model. Our calculations reveal that the development of a collision cascade in δ-Pu is highly different from what is known for other face-centered-cubic metals. We observe that the disordered region induced by the melting of the cascade core is curiously stable for tens of nanoseconds. The causes of this unusual behavior are examined on the basis of the above-mentioned parametric study.