Implementation of a Fe-He Three-body Interatomic Potential

Abstract

The implementation of a recently-developed interatomic potential describing the interactions of helium in bcc iron is described. This He-Fe potential was based on an empirical fit to the results of ab initio calculations of both the formation and relaxation energies of small helium defect structures in iron. The fitting database included substitutional and interstitial helium, as well as small helium and helium-vacancy clusters. In contrast to previous He-Fe pair potentials, fitting the ab initio forces and energies required the use of a three-body interaction term. The implementation of this potential for atomistic simulations using molecular dynamics presented certain challenges which are discussed here to facilitate its further use in materials research, particularly to investigate the behavior of iron-based alloys that may be employed in fusion energy systems.