Accelerated molecular dynamics simulation of vacancy diffusion in substitutional alloy with collective variable-driven hyperdynamics

H Ebina and S Fukuhara and Y Shibuta, COMPUTATIONAL MATERIALS SCIENCE, 196, 110577 (2021).

DOI: 10.1016/j.commatsci.2021.110577

It is not straightforward to investigate diffusion-limited phenomena in solid system by molecular dynamics (MD) simulation due to the limitation in time scale. Although many methods have been developed to extend the MD time scale by accelerating infrequent events, there is no established technique to treat diffusion in substitutional solid solution up to now since motions of solute atom, matrix atoms and vacancy interact each other complexly. In this study, an acceleration technique for the MD simulation of diffusion in substitutional solid solution is developed in conjunction with collective variable-driven hyperdynamics (CVHD). This novel technique is applied for the diffusion in Fe-Cr alloy as a representative substitutional alloy. Activation energy of vacancy diffusion from accelerated CVHD simulation basically agrees with that derived from MD simulation without acceleration, which confirms that the accelerated CVHD simulation reproduces the dynamics of vacancy diffusion in substitutional solid solution correctly.

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