Thermal fluctuations of dislocations reveal the interplay between their core energy and long-range elasticity

Equilibrium fluctuations of dislocations are central to the plastic response of metals and alloys because they control the attempt frequency of thermally activated events. We analyze here atomic-scale simulations of thermally vibrating dislocations with the help of an analytical model and show that thermal fluctuations intimately involve both long-range elasticity and short-range core effects. In addition, equilibrium fluctuations of edge and screw dislocations in aluminum are used to derive quantitative parameters that characterize their energetics and dynamics and we discuss how large-scale models such as dislocation dynamics can be parametrized based on these results. In particular, we show that the core parameters found here through fluctuations are transferable and can be used to predict dislocation bow-out under an applied stress.