A new type angular-dependent interatomic potential and its application to model displacement cascades in uranium

Abstract

A new type angular-dependent potential has been proposed to describe atomistic interaction of uranium. It consists of three part contributions, namely pair, embedded and angular-dependent parts, to the system energy, in which the former two parts are based on embedded-atom method (EAM), and the last one is inspired by modified embedded-atom method (MEAM). It turns out that the new potential can reproduce well the cohesive energy, lattice constants and elastic constants of α-U and γ-U. Moreover, compared to previous EAM and MEAM potentials for uranium in literature, the new proposed potential can describe the formation energies of the relaxed vacancy and interstitial more precisely. In addition, the calculation efficiency of the potential is higher than that of MEAM. Applying this potential, the displacement cascades in α-U have been studied via molecular dynamics simulation. Calculation suggests a wide displacement threshold energy for α-U ranging from 12 to 57 eV. However, the number of defects is almost independent to the primary knock-on atom (PKA) direction when the PKA energy is same and greater than 1 KeV, suggesting a low anisotropy of α-U in the process of displacement cascades.