A THEORY OF HYDROGEN TRAPPING IN A FAULTED ZONE OF FCC IRON

The energetics of hydrogen atoms interacting with a cluster model of g amma-Fe, having a stacking fault zone, have been investigated. The sys tem energy is calculated using the atom superposition and electron del ocalization molecular orbital (ASED-MO) method. By modifying the geome trical positions of the impurity within the cluster we found that H oc cupies nearly octahedral sites on a stacking fault plane. A second H r esiding near the former and the possible formation of H-H pairing is a lso addressed. The relative stability of H-H pairs in the iron matrix is; compared with that of the Ha molecule, in the vacuum.