The Effect of Crystal Symmetries on the Locality of Screw Dislocation Cores

TL;DR

This paper shows that exploiting crystal symmetries can significantly improve the decay rate of dislocation core corrections in elastic fields, enhancing the accuracy of continuum models and atomistic simulations.

Contribution

It demonstrates that full symmetry utilization leads to decay rates faster than previously established, improving predictions of dislocation core behavior in materials.

Findings

Decay rate of core correction improves to O(r^{-p}) with p > 2 when symmetries are used

Continuum elasticity can predict dislocation fields more accurately than expected in symmetric crystals

Implications for more precise atomistic simulations of dislocation cores

Abstract

In linearised continuum elasticity, the elastic strain due to a straight dislocation line decays as $O(r^{-1})$, where $r$ denotes the distance to the defect core. It is shown in Ehrlacher, Ortner, Shapeev (2016) that the core correction due to nonlinear and discrete (atomistic) effects decays like $O(r^{-2})$. In the present work, we focus on screw dislocations under pure anti-plane shear kinematics. In this setting we demonstrate that an improved decay $O(r^{-p})$, $p > 2$, of the core correction is obtained when crystalline symmetries are fully exploited and possibly a simple and explicit correction of the continuum far-field prediction is made. This result is interesting in its own right as it demonstrates that, in some cases, continuum elasticity gives a much better prediction of the elastic field surrounding a dislocation than expected, and moreover has practical implications for atomistic simulation of dislocations cores, which we discuss as well.