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Applied Surface Science, Vol.173, No.3-4, 368-379, 2001
The electronic structure and location of H pairs in bcc Fe edge dislocation
The H-Fe interaction near an edge dislocation line was studied using qualitative electronic calculations in the framework of the atom superposition and electron delocalisation molecular orbital (ASED-MO) theory. Calculations were performed using a Fe-207 cluster to simulate a dislocated bcc structure. The cluster geometry and atomic parameters were optimised to make a better approximation to the repulsive energy terms. The final localisation of two H atoms inside the cluster were determined as they entered from the (0 0 1) surface. The results indicate that the H-Fe interaction is stronger near the dislocation, making it a possible region for H accumulation. Changes in the electronic structure of bcc dislocated Fe were analysed for the system without H, with one H atom and with two H atoms. Fe atoms surrounding the dislocation line which are initially more strongly bonded with each other than the bulk Fe atoms weaken their bond when H is present. This is due to the formation of an H-Fe bond. H influences only its nearest Fe atoms. The H-H interaction was also analysed.