New interatomic potentials for studying the behavior of noble gas atoms in tungsten

To study the behavior of noble gas atoms (He, Ne and Ar) in bulk tungsten, new DFT-based potentials for W–He, W–Ne and W–Ar interactions were developed by fitting the results obtained from density functional theory calculations.

The new potentials adopt the embedded atom method (EAM) formalism, and the “s-band model” is used to describe the many-body interactions between each of the noble gas atoms and its neighboring W atoms. These potentials reproduce the formation energies of point defects and the migration barriers of single noble gas atoms.

The simulations using these potentials successfully predict that the tetrahedral interstitial site is more stable than the octahedral interstitial site for X (= He, Ne or Ar) interstitials. Based on these new potentials, the binding interactions of a single X atom with the X_n and X_n–Vacancy clusters and the diffusion properties of X_n clusters in bulk W were studied using molecular dynamics (MD) simulations.

The present results indicate that the binding energies obtained using the new potentials are good in agreement with the results of DFT calculations. The migration energies of the clusters increase with both the increase in the atomic radius of noble gases and the increase in the size of the clusters.

This article originally appeared in Journal of Nuclear Materials 467, Part 1, 2015, Pages 398–405.