Measurement of Twin Formation Energy Barriers Using Nudged Elastic Band Molecular Statics

Abstract

The nudged elastic band (NEB) method [1, 2] is used to find the energy barrier separating stable twinned and untwinned states in Magnesium. This technique enables identification of the minimum energy path between the two stable states. The effects of dislocations, grain boundaries, and other defects which enhance twin nucleation produce a measurable effect on the minimum energy path [3, 4] and energy barrier. Thus, the NEB technique enables direct comparisons of the material twin-ability under a variety of boundary conditions. By simulating twinning in a variety of boundary conditions, NEB calculations provide key insight into the twin nucleation process by demonstrating both what defect arrangements encourage twin nucleation, and how likely twinning is to occur under given boundary conditions. This data is crucial for incorporating twin nucleation accurately into higher scale modeling.