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The formation and migration energies of the mono- and di-vacancy in Mg crystal have been calculated using the modified analytical embedded atom method. The results show that, for mono-vacancy, the migration in the basal plane is slightly preferred to the migration out of the basal plane. For di-vacancy, the 1NN and 2NN configurations are not only easier to form but also more stable than the other configurations. The preferred migration mechanisms of the 1NN and 2NN di-vacancy are either invariable 1NN or 2NN configurations during migration in the basal plane or exchange 1NN for 2NN or 2NN for 1NN for migration out of the basal plane. These two-jump migration mechanisms of the di-vacancy, especially the former, are still preferred over the migration of the mono-vacancy. It is concluded that the greater the number of resting vicinity vacancies, the easier the migrating vacancy moves. [ABSTRACT FROM AUTHOR]

In this paper, the stability of various atomic configurations containing a self-interstitial atom (SIA) in a model representing α-iron is investigated. From the energy panorama maps of the SIA located in possible non-equivalent interstitial sites, six relatively stable self-interstitial sites are found, whose structures and formation energies have been described and calculated using the modified analytical embedded atom method and molecular dynamics. The simulation results indicate that the [110] dumbbell interstitial is the energetically most favorable configuration, which is in good agreement with the experimental and ab initio results, and the distances between two displaced atoms that compose the [100], [110] and [111] direction dumbbells have been computed to be 0.68a, 0.65a and 0.29a, respectively, not all being about 0.75a apart. The relaxed displacements up to the fifth-nearest-neighbor atoms around the SIA in O interstitial position are also calculated. [ABSTRACT FROM AUTHOR]