A model for atomic hydrogen-bimetal interactions

S. SIMONETTI; G. CANTO

Congreso; 4º Congreso Nacional - 3° Congreso Iberoamericano -HIDRÓGENO Y FUENTES SUSTENTABLES DE ENERGíA- HYFUSEN; 2011

The adsorption of atomic H on the FeNi(111) surface has been studied by ASED-MO tight binding calculations. The energy of the system was calculated by the atom superposition and electron delocalization molecular orbital (ASED-MO) method. Seven H locations on the alloy surface were selected and the hydrogen atom was positioned in their energy minima configurations. By ASED-MO calculations, the H atom presents its most stable geometries when it bonds on top Fe atom at 1.5 Å and on bridge Fe-Fe at 0.7 Å, respectively.  In these cases, the strength of the local Fe-Fe bond decreases 12 % and 33% of its original bulk value, respectively. As a consequence of H-Fe interaction, a decohesion mechanism in the Fe-Fe bond could be evidenced. On the other hand, the Fe-Ni and Ni-Ni superficial bonds are slightly fortified between 0.5-2 %. A discussion based on electronic structure studies using the concept of density of states (DOS) and crystal orbital overlap population (COOP) curves are presented.