Nudged-Elastic Band Study of Lithium Diffusion in Bulk Silicon in the Presence of Strain

We study the effect of strain on the lithium diffusion barrier in diamond cubic Si using nudged-elastic band (NEB) method. The modified embedded atom method (MEAM) interatomic potential is employed to describe the interactions between Li and Si atoms. The activation barrier and minimum energy path is found to change significantly as the biaxial strain changes from compressive to tensile in nature. The local strain arising from the presence of neighboring Li atoms is found to affect the activation barrier even more. The Si-Si bond stretching and breaking events during Li diffusion are investigated to elucidate the change in barrier with changing local environment and strain. This study highlights that bulk strain as well as local strain arising from the presence of Li atoms in the vicinity of a diffusing Li atom can affect the Li diffusion constant by orders of magnitude.