Identification of self-interstitial atoms and vacancies in crystalline materials in atomistic simulation

As the most important intrinsic point defects, self-interstitial atoms and vacancies play crucial roles in governing the microstructural evolution in crystalline materials. In atomistic simulation, the self-interstitial atoms and vacancies are identified by various location methods, such as the Wigner-Seitz cell method. Here we reveal that the mobile defects will give rise to the random drift of the simulation system with periodic boundary conditions, which may lead to the failure of commonly used location methods, ultimately resulting in the wrong determination of self-interstitial atoms and vacancies in the evolution of crystalline materials. Usually, it is a slow process that is not easily observed, therefore, a special attention is required when identifying the intrinsic point defects in the long time scale evolution. Moreover, a correction method is proposed to avoid the failure of location methods.