Trapping of multiple hydrogen atoms in a vanadium monovacancy: A first-principles study

First-principles calculations were performed to illustrate the trapping mechanism of multiple hydrogen atoms in a monovacancy of vanadium solid in terms of the stability of hydrogen–vacancy (mH–VA) complexes and H–H interactions. The preferential site for single H is not vacancy center but close to octahedral interstitial site with solution energy of −0.67 eV. Lower electron density in the presence of vacancy explains why H impurities can be easily trapped at vacancy. Among the possible mH–VA complexes, the 2H–VA conjuration is the most stable complex energetically. According to computed trapping energies, up to six H atoms can be trapped in one monovacancy inside vanadium solid. We also found that H2 molecule is extremely difficult to survive in a small vacancy complex. The present results provide an elementary picture of the H trapping mechanism as well as H bubble formation in vanadium solid.