The electronic effect of N impurity in an 〈1 0 0〉 edge dislocation core system in α-iron

First-principles methods are employed to investigate the structure relaxation and the electronic structure of a N impurity in an 〈1 0 0〉 edge dislocation core (DC) system in α-iron. A 96-atom cluster model is used to simulate the local environment of N impurity in the edge dislocation. By use of the DMol method, we obtained an optimized atomic configuration for the system by calculating the forces on N impurity and its neighboring Fe atoms, and by minimizing the total energy of the cluster model. The optimization results show that the N impurity moves away from compression region to a stable position in the dilated region. By use of the discrete variational (DV) method, we calculated energetic parameters (structural energy and interatomic energy) and charge distribution. From these results, one can find that N impurity has a strong interaction with its adjacent Fe atoms in the DC system. Moreover, notable charge redistribution between the N impurity and Fe atoms indicates the formation of N impurity–Fe dislocation complex, which implies the trapping effect of DC on N impurity.