The electronic structure and bonding of hydrogen near a fcc Fe stacking fault

The atom superposition and electron delocalization molecular orbital (ASED- MO) semiempirical method is used to analyse the atomic hydrogen-Fe interact ion. The face centred cubic (fcc) Fe model contains a stacking fault and as a comparison the H-fcc Fe (normal) system is also studied. The solid is re presented by a cluster of 180 metallic atoms distributed in five layers. Th e interstitial atoms localized in different geometric positions found an en ergetic minimum in a zone close to octahedral interstitial holes in the sta cking fault. The electronic structure shows that the H-Fe bond involves mai nly the Fe 4s and 4p orbitals and the is H orbital. The Fe-Fe bond near H i s destabilized, to approximately 27% of its original value.