Atomistic corroboration of a multiscale approach for the analysis of dislocation nucleation at a surface step

Abstract

The variational boundary integral formulation of the Peierls-Nabarro dislocation model has recently become one of the most effective multiscale approaches for the analysis of dislocation nucleation problems. By representing the structure of a dislocation as the relative displacement between two adjacent atomic layers along the slip plane, the model allows for the convenient incorporation of atomic information to treat the deformation of the dislocation core as continuous deformation, therefore eliminating the uncertain core cutoff parameter associated with the singularity of continuum elastic dislocation theory. By reducing many atomic degrees of freedom to fewer, yet more physically intuitive, degrees of freedom in this multiscale approach, one may gain a greater understanding of relevant physical processes in larger systems with more realistic geometries. Application of this approach requires the understanding of the reliability of this approach, or at least, it correlation to that of all atom calculations. Using nucleation of a 〈111〉 screw dislocation at a step from a {112} surface of tantalum as an example, this paper provides an atomistic corroborative study of this multiscale approach. The results show the critical stresses for dislocation nucleation in this configuration obtained by the multiscale approach are in good agreement with all atom calculations. © 2007 Springer.