Investigation of the Adsorption and Diffusion of Hydrogen in Iron Clusters by the Method of Density Functional

We construct a cluster model of interaction of atomic hydrogen with α - and γ -iron surfaces and perform quantum-chemical computations of the Fe–H system by the method of density functional with the RPBE-GGA exchange-correlation functional. We obtain the curves of the potential energy of interaction of atomic hydrogen with iron clusters of BCC and FCC structures and establish the activation barriers of its adsorption, penetration into the subsurface layer, and migration between tetrahedral and octahedral positions of clusters. The energies of dissolution of atomic hydrogen at different absorption sites of the clusters are computed and the stable energy states of hydrogen in the octahedral positions of FCC iron clusters are revealed. We analyze the charge state of atomic hydrogen both on the surface and in the bulk sites of the clusters and confirm the mechanism of partial charge transfer in the iron–hydrogen system.