Dislocation Core Energies and Core Fields from First Principles

TL;DR

This paper uses first-principles calculations to identify a dislocation core field in bcc iron, improving elastic models and enabling more accurate, size-independent core energy calculations.

Contribution

It introduces a method to incorporate a dislocation core field into elastic theory, enhancing the accuracy of core energy estimations from ab initio data.

Findings

Identification of a <111> screw dislocation core field in bcc iron

Improved elastic modeling with force dipoles

Faster convergence of core energy calculations

Abstract

Ab initio calculations in bcc iron show that a <111> screw dislocation induces a short-range dilatation field in addition to the Volterra elastic field. This core field is modeled in anisotropic elastic theory using force dipoles. The elastic modeling thus better reproduces the atom displacements observed in ab initio calculations. Including this core field in the computation of the elastic energy allows deriving a core energy which converges faster with the cell size, thus leading to a result which does not depend on the geometry of the dislocation array used for the simulation.