The electronic effect in the ⟨100⟩ edge dislocation core system with a carbon atom inα-iron: a first-principles study

Abstract

Using the DMol molecular cluster method and the self-consistentdiscrete variational method based on density functional theory, weinvestigated the electronic effect in the ⟨100⟩ edgedislocation core system with a C atom in α-iron. A clustermodel containing 96 atoms was used to simulate the local environmentof the Fe edge dislocation, and the optimization results show that the Catom moves away from the compression side to the dilated region andfalls into a flat tetrahedral interstice composed of four adjacent Featoms. We present the characteristic parameters including thestructural energy, the interatomic energy, the partial density ofstates and the charge-density difference of the dislocation coresystem. The results suggest that the C atom stays steadily at afavourable site in the tetrahedron and forms strong covalent-likebonds with its adjacent Fe atoms. Moreover, the remarkable chargeredistribution and the large binding energy drop in the dislocationcore system indicate the formation of a C impurity-Fe edgedislocation complex which implies an effect of trapping of thedislocation core on the C atom.