The effect of crystal symmetries on the locality of screw dislocation cores

In linearized 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 [V. Ehrlacher, C. Ortner, and A. V. Shapeev, Arch. Ration. Mech. Anal., 222 (2016), pp. 1217-1268] 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 antiplane 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.