A new Fe–He interatomic potential based on ab initio calculations in α-Fe

A new interatomic potential for Fe–He interactions has been developed by fitting to the results obtained from ab initio calculations. Based on the electronic hybridization between Fe d-electrons and He s-electrons, an s-band model, along with a repulsive pair potential, has been developed to describe the Fe–He interaction. The atomic configurations and formation energies of single He defects and small interstitial He clusters are utilized in the fitting process. The binding properties and relative stabilities of the He–vacancy and interstitial He clusters are studied. The present Fe–He potential is also applied to study the emission of self-interstitial atoms from small He clusters in α-Fe matrices. It is found that the di-He cluster dissociates when the temperature is higher than 400 K, but the larger He clusters can create an interstitial Fe atom. The temperature for kicking out an interstitial Fe atom is found to decrease with increasing size of the He clusters.