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Using the DMol molecular cluster method and the self-consistent discrete variational method based on density functional theory, we investigated the electronic effect in the ⟨100⟩ edge dislocation core system with a C atom in α-iron. A cluster model containing 96 atoms was used to simulate the local environment of the Fe edge dislocation, and the optimization results show that the C atom moves away from the compression side to the dilated region and falls into a flat tetrahedral interstice composed of four adjacent Fe atoms. We present the characteristic parameters including the structural energy, the interatomic energy, the partial density of states and the charge-density difference of the dislocation core system. The results suggest that the C atom stays steadily at a favourable site in the tetrahedron and forms strong covalent-like bonds with its adjacent Fe atoms. Moreover, the remarkable charge redistribution and the large binding energy drop in the dislocation core system indicate the formation of a C impurity-Fe edge dislocation complex which implies an effect of trapping of the dislocation core on the C atom.

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