Homogeneous and heterogeneous nucleation of Lennard-Jones liquids

Comparing crystal-melt interfacial free energies through homogeneous nucleation rates

In this work, we compared several available crystal-melt interfacial free energies via homogeneous nucleation rates in a pure Lennard-Jones model system using both model fitting and numerical methods. We examined the homogeneous nucleation temperature obtained from the classical nucleation theory using the available interfacial free energies from three different methods as inputs, i.e. the free energy integration method, the interface fluctuation method and the classical nucleation theory based method. We found that the critical temperature obtained by using the interfacial free energy calculated recently (Bai and Li 2006 J. Chem. Phys. 124 124707) is in better agreement with that obtained from spontaneous crystallization in an independent molecular dynamics simulation. The discrepancies among the interface energies are discussed in light of these results.

Modification of the classical nucleation theory based on molecular simulation data for surface tension, critical nucleus size, and nucleation rate

Nucleation in supersaturated vapor is investigated with two series of molecular-dynamics simulations in the canonical ensemble. The applied methods are (a) analysis of critical nuclei at moderate supersaturations by simulating equilibria of single droplets with surrounding vapors in small systems; (b) simulation of homogeneous nucleation during condensation with large systems containing 10(5)-10(6) particles for calculating the nucleation rate of vapors at high supersaturations. For the Lennard-Jones fluid, truncated and shifted at 2.5 times the size parameter, it is shown that the classical nucleation theory underestimates both the nucleation rate and the size of the critical nucleus. A surface property corrected modification of this theory is proposed to consistently cover data on the surface tension of the curved interface, the critical nucleus size, and the nucleation rate.