The electronic effect in the < 100 > edge dislocation core system with a carbon atom in alpha-iron: a first-principles study

Using the DMol molecular cluster method and the self-consistent discrete va riational method based on density functional theory, we investigated the el ectronic effect in the < 100 > edge dislocation core system with a C atom i n cr-iron. A cluster model containing 96 atoms was used to simulate the loc al environment of the Fe edge dislocation, and the optimization results sho w that the C atom moves away from the compression side to the dilated regio n and falls into a flat tetrahedral interstice composed of four adjacent Fe atoms. We present the characteristic parameters including the structural e nergy, the interatomic energy, the partial density of states and the charge -density difference of the dislocation core system. The results suggest tha t the C atom stays steadily at a favourable site in the tetrahedron and for ms strong covalent-like bonds with its adjacent Fe atoms. Moreover, the rem arkable charge redistribution and the large binding energy drop in the disl ocation core system indicate the formation of a C impurity-Fe edge dislocat ion complex which implies an effect of trapping of the dislocation core on the C atom.