Lowest energy structures of self-interstitial atom clusters in α-iron from a combination of Langevin molecular dynamics and the basin-hopping technique

Abstract

A combination of simulated annealing with Langevin molecular dynamics and the basin-hopping with occasional jumping (BHOJ) technique was used to systematically determine the most stable configurations of self-interstitial atom (SIA) clusters I _n (n = 1–38) in α-iron. In addition to the original BHOJ technique, we introduced an additional long jumping process in which a randomly selected less-bounded atom is moved to a neighbouring site of another SIA in the cluster to enhance the probability of locating the global minimum structure. With the obtained putative lowest energy structures, the binding energies as a function of cluster size were estimated. We also determined the sizes of particular stable clusters based on their geometrical symmetry. Furthermore, the values were extrapolated based on accurately determined formation energies, and are available for immediate use in kinetic Monte Carlo or rate theory models.

Keywords:

• Langevin molecular dynamics
• basin-hopping with occasional jump
• Monte Carlo minimisation
• simulated annealing
• self-interstitial cluster
• α-iron