First-principles study of vacancy, interstitial, noble gas atom interstitial and vacancy clusters in bcc-W

Based on first-principles calculations, the vacancy and self-interstitial formation energy in bcc-W are 3.19 eV and 9.97 eV. Binding energy between the dumbbell interstitials can be up to 2.29 eV. Binding energy for the first and second nearest neighbor vacancy pair are -0.12 eV and -0.41 eV. The migration barrier of vacancy, He, Ne and Ar interstitial are 1.70 eV, 0.07 eV, 0.15 eV and 0.25 eV. The migration barrier of self-interstitial along 111 is 0.05 eV. The so-called rotation barrier of self-interstitial is 0.35 eV. The formation energy of He, Ne, Ar substitutional and He, Ne, Ar tetrahedral interstitial are 4.85 eV, 6.42 eV, 9.54 eV and 6.23 eV, 10.40 eV, 15.10 eV, respectively. Binding energy for di-gas atom (He, Ne and Ar) interstitial are 0.95 eV, 2.28 eV and 1.70 eV. The binding energy of noble gas atom interstitial and vacancy cluster are obtained and can be used as an input to build a molecular dynamics (MD) W-Ne potential. Then molecular dynamics (MD) simulations can be used to investigate the mechanism and temperature dependence of the surface modification of plasma-facing tungsten in the application of future fusion reactors in the following investigations. (C) 2016 Elsevier B.V. All rights reserved.