Application of hyper-molecular dynamics to self-interstitial diffusion in α-iron

•The hyper-MD method can significantly accelerate the SIA diffusion dynamics.•The diffusivity can be adequately calculated even at low temperatures.•The successful application will lead to the use of the method for other systems.

The diffusion process of a single self-interstitial atom (SIA) in α-iron was studied by a hyper-molecular dynamics (hyper-MD) method that has been demonstrated to efficiently accelerate slow diffusive conformational transitions that occur in various materials. By adding a local bias potential, the acceleration of the dynamics becomes significantly higher at lower temperatures, e.g., on the order of 5 at 300 K, without changing the dynamics of the diffusion process as calculated using a conventional MD simulation. The validity of the results demonstrates that the hyper-MD method with an appropriate local bias potential can be applicable for determination of the diffusion process of SIAs in bulk materials.