Calculations of diffusion in FCC binary alloys using on-the-fly kinetic Monte Carlo

We present a systematic, microscopic approach to diffusion for intermetallic alloys using accelerated molecular dynamics. On-the-fly kinetic Monte Carlo is combined with an efficient saddlepoint search to find the saddlepoints exiting a valley, based on energetics from the embedded atom method. With this technique, we compute the tracer diffusivities, migration energies, short-range order and long-range order as a function of composition and temperature for examples of moderately ordered (Cu3Au), weakly ordered (Au-Ag) and weakly clustered (Cu-Ni) alloys. We find that away from any critical temperature, the calculations produce reliable results, but when critical behavior dominates the approach is overcome by critical fluctuations.