Computer simulation studies of the a/2 〈111〉 edge dislocation in α-iron

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Abstract
Core characteristics of the stable a/2 〈111〉 edge dislocation in α‐iron are presented for three two‐body interatomic potentials, and the importance of properly defining boundary conditions is demonstrated. The boundary requirements adopted for this analysis are as follows: (i) The coordinate of the dislocation line along the axis parallel to the burgers vector is such that, above and below the slip plane, the lattice to the right and left of the extra half‐planes of atoms forming the dislocation is symmetric. (ii) The coordinate of the dislocation line in the direction perpendicular to the slip plane is such that the slope of the strain energy curve in the linear region of the lattice agrees with the slope in the continuum. (iii) The positions of atoms at the lattice‐continuum interface are made to agree with the predictions of linear elasticity theory. Four interatomic potentials are examined, one of which is shown to be unsatisfactory. Results with the other three potentials are quite reasonable. Core radii of 4.6, 4.8, and 5.4 Å and corresponding core energies of 0.479, 0.539, and 0.701 eV per (112) plane are calculated. The stable core configuration in each case is consistent with the particular character of the interatomic potential. The results suggest that the core characteristics are not sensitive to the value of the cohesive energy associated with each potential.