Accurate atomistic simulation of (a/2) 〈111〉 screw dislocations and other defects in bcc tantalum

Abstract

Abstract The fundamental atomic-level properties of (a/2)(111) screw dislocations and other defects in bcc Ta have been simulated by means of new quantum-based multi-ion interatomic potentials derived from the model generalized pseudopotential theory (MGPT). The potentials have been validated in detail using a combination of experimental data and ab-initio electronic structure calculations on ideal shear strength, vacancy and self-interstitial formation and migration energies, grain-boundary atomic structure and generalized stacking-fault energy (γ) surfaces. Robust and accurate two- and three-dimensional Green's function (GF) techniques have been used to relax dynamically the boundary forces during the dislocation simulations. The GF techniques have been implemented in combination with a spatial domain decomposition strategy, resulting in a parallel MGPT atomistic simulation code that increases computational performance by two orders of magnitude. Our dislocation simulations predict a degenerate core str...