Many-body potential for nitrogen in α-iron

Abstract N atom is one of the most frequent foreign interstitial atoms in α-iron along with C atoms. The Fe–C potential has been well-developed and can reproduce many significant interactions of C with point defects present in α-iron. However, there exists no satisfactory Fe–N potential to describe the interactions of N with point defects. Here, we develop a many-body potential for N in α-iron. The potential parameters are determined by fitting to ab initio data, which includes energetics, configurations, and relaxations of Fe atoms close to N atom. This potential successfully describes the interactions of Fe–N across a wide range of defect environments. The potential employs the embedded atom method form and hence is appropriate for large-scale molecular dynamics simulation. Keywords: Fe–N systeminteratomic potentialembedded atom methodpoint defectsmolecular dynamic simulationfirst-principles calculation Acknowledgments We gratefully acknowledge the National Natural Science Foundation of China (Grant No. 51 071 061) and NSAF (Grant No. 11 176 011) for the financial support of this research work. Y.Y. is very grateful to Dr Derek Hepburn for his answers about spline functions and suggestions for fitting a potential.