Solid-liquid interface free energy through metadynamics simulations

The solid-liquid interface free energy gamma(sl) is a key parameter controlling nucleation and growth during solidification and other phenomena. There are intrinsic difficulties in obtaining accurate experimental values, and the previous approaches to compute gamma(sl) with atomistic simulations are computationally demanding. We present an approach which is to obtain gamma(sl) from a free-energy map of the phase transition reconstructed by metadynamics. We apply this to the benchmark case of a Lennard-Jones potential, and the results confirm the most reliable data obtained previously. We demonstrate several advantages of our approach: it is simple to implement, robust and free of hysteresis problems, it allows a rigorous and unbiased estimate of the statistical uncertainty, and it returns a good estimate of the thermodynamic limit with system sizes of a just a few hundred atoms. It is therefore attractive for applications which require more realistic and specific models of interatomic forces.