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.