The interaction between two-hydrogen atoms and a γ-Fe structure containing a vacancy was studied using a cluster model and a theoretical method. For the study of the sequential absorption, the hydrogen atoms were positioned in their energy minima configurations, near the vacancy. The interactions mainly involve Fe 4s–H 1s atomic orbitals. The contribution of Fe 4p and Fe 3d orbitals was much less important. The Fe–Fe bond was weakened as new Fe–H–H and H–H pairs were formed. The effect of H atoms was limited to its first Fe neighbours. The Fe–Fe bond strength decreases with the introduction of the H atoms. Fe–H bonding was achieved at expense of weakening the metal–metal nearest bonds. There was not a real bond between the H atoms but some H–H interaction was observed. The detrimental effect of H atoms on the Fe–Fe bonds could be related to one of the aspect of embrittlement in γ-Fe.

The Effects of a Hydrogen Pair in the Electronic Structure of the FCC Iron Containing a Vacancy. S.Simonetti, D.R.Saravia, G.Brizuela, A.Juan: International Journal of Hydrogen Energy, 2010, 35[11], 5957-62