Diffusivity, Interfacial Free Energy, and Crystal Nucleation in a Supercooled Lennard-Jones Liquid

We carried out extensive molecular dynamics simulations of seeded crystallization in a Lennard-Jones liquid in a wide range of supercoolings under zero external pressure. The number of particles in the critical crystal nucleus, n*, the particle transport coefficient at the liquid/nucleus interface, D-* the crystal pressure, p(s)*, the crystal density, ps*, and the thermodynamic driving force, Delta mu = ps*/ps*, were determined at 11 temperatures. We used the classical nucleation theory (CNT) to calculate the effective nucleus/liquid interfacial free energy, gamma(e). The results of seeded crystallization fit rather well to those of a previous work on spontaneous crystallization and show that ye monotonically increases with temperature. Using the physical properties determined from the computer simulations: ps*, rho s*, n*, Delta mu, and the equilibrium melting temperature, we calculated the steady-state crystal nucleation rates, J(T). The agreement with a value determined from spontaneous nucleation was excellent, demonstrating the validity of the CNT, as opposed to the often-reported colossal discrepancies between the theoretical and experimental values of nucleation rates. A key factor to explain this agreement is that we used correct, directly determined physical parameters. In this work, n*(T), Delta mu(T), and D-*(T) obtained from the simulations were used instead of (fitted) average interfacial energy, calculated Ay, and other approximations, such as viscosity or nucleation timelags, for the transport term in the analysis of experimental nucleation rates.