Stability and diffusion properties of self-interstitial atoms in tungsten: a first-principles investigation

Employing a first-principles method based on the density function theory, we systematically investigate the structures, stability and diffusion of self-interstitial atoms (SIAs) in tungsten (W). The〈111〉 dumbbell is shown to be the most stable SIA defect configuration with the formation energy of ∼9.43 eV. The on-site rotation modes can be described by a quite soft floating mechanism and a down-hill “drift” diffusion process from 〈110〉 dumbbell to 〈111〉 dumbbell and from 〈001〉 dumbbell to 〈¹10〉 dumbbell, respectively. Among different SIA configurations jumping to near neighboring site, the 〈111〉 dumbbell is more preferable to migrate directly to first-nearest-neighboring site with a much lower energy barrier of 0.004 eV. These results provide a useful reference for W as a candidate plasma facing material in fusion Tokamak.