Metadynamics for Vacancy Dynamics in Crystals

Abstract

We propose a metadynamics-based (MetaD-based) approach to construct the free energy surface (FES) for vacancy dynamics in crystals. In this approach, the vacancy FES can be constructed without explicitly defining a unique vacancy coordinate by introducing a set of parameters that strongly govern the FES, which is enabled by parallel bias MetaD with partitioned families (PB-MetaDPF). In addition, the proposed approach is made more efficient and effective by multihill strategy that exploits crystallographic symmetry. We demonstrate the validity and efficacy of the proposed approach by its applications to self-diffusion and impurity diffusion via monovacancies and divacancies in metallic and ionic crystals.