Hydrogen assisted vacancy formation in tungsten: A first-principles investigation

The effects of hydrogen induced vacancy formation in tungsten have been investigated with a first-principles method based on the density functional theory. Hydrogen is demonstrated to assist the formation of vacancy and such effect is enhanced with increasing of hydrogen concentration. Using the energy of a single tungsten atom for the bulk as the reference energy, a spontaneous vacancy formation in tungsten is observed when more than two hydrogen atoms are introduced. These results provide a good explanation for creation of super-abundant vacancies in tungsten and can contribute to understand the mechanism of hydrogen bubble formation.