Quantum Peierls stress of straight and kinked dislocations and effect of non-glide stresses

Abstract

It was recently shown that to predict reliable Peierls stresses from atomistic simulations, one has to correct the Peierls barrier by the zero-point energy difference between the initial and activated states of the dislocation. The corresponding quantum Peierls stresses are studied here in {\alpha}-Fe modeled with two embedded atom method potentials. First, we show that the quantum correction arises from modes localized near the dislocation core, such that partial Hessian matrices built on small cylinders centered on the dislocation core can be used to compute the zero-point energy difference. Second, we compute quantum Peierls stresses for straight and kinked dislocations and show that the former is smaller than the latter with both {\alpha}-Fe models. Finally, we compare quantum Peierls stresses obtained in simple shear and in traction along two orientations considered experimentally by Kuramoto et al., evidencing a strong effect of non-glide stresses on the quantum Peierls stress.