Overcoming the time limitation in Molecular Dynamics simulation of crystal nucleation: a persistent-embryo approach

The homogeneous crystal nucleation from liquid in most cases is too rare to be accessed within the limited timescales of the conventional molecular dynamics (MD) simulation. In this talk, we present a “persistent embryo” method to facilitate crystal nucleation in MD simulations. We applied this method to the pure Ni for a moderate undercooling where no nucleation can be observed in the conventional MD, and obtained nucleation rate in good agreement with the experimental data. With MD simulation, we were able to describe the shape of the nucleus and derived the interfacial free energy as a function of the temperature. Moreover, the method is applied to simulate an even more sluggish event: the nucleation of the B2 phase in a strong glass-forming Cu-Zr alloy. The nucleation rate was found to be 8 orders of magnitude smaller than Ni at the same undercooling, which well explains the good glass formability of the alloy. This work opens a new way to study solidification under realistic experimental conditions via atomistic computer simulation.