First-principle calculations of hydrogen interaction with vacancies and dissolved atoms in tungsten

Hydrogen interaction with vacancies and dissolved carbon atoms in tungsten lattice were examined by means of the density functional method implemented with VASP code. Appreciable binding energies of multiple hydrogen atoms with mono-vacancy were obtained in this study. Based on the calculated binding energies, it was shown that elevated atomic concentration of ambient hydrogen atoms increased the vacancy-hydrogen complex abundance in the tungsten lattice. Binding energies of single hydrogen atom in di-vacancies were calculated to be significantly larger than that of the mono-vacancy. This large binding energy assists the vacancy association. Repulsive interaction between neighboring hydrogen atom and carbon atom in the interstitial of the tungsten lattice was predicted in this study. (author)