No Evidence of Anomalous Diffusion in Yukawa Crystals

Abstract

Diffusion in Yukawa crystals is stochastic due to the thermally activated formation of vacancy-interstitial pairs, which have poor statistics in simulations. This makes it difficult to argue if Yukawa crystals exhibit normal diffusion, or if they could be subdiffusive or superdiffusive. To resolve this, we run a long molecular dynamics simulation of an idealized Yukawa crystal for a billion timesteps. We find no evidence of anomalous diffusion in the pure crystal, but also caution readers against overinterpreting this result as real crystals have complicated structures including grains and defects.