Extraction of effective solid-liquid interfacial free energies for full 3D solid crystallites from equilibrium MD simulations

Molecular dynamics simulations of an embedded atom copper system in the isobaric-isenthalpic ensemble are used to study the effective solid-liquid interfacial free energy of quasi-spherical solid crystals within a liquid. This is within the larger context of molecular dynamics simulations of this system undergoing solidification, where single individually prepared crystallites of different sizes grow until they reach a thermodynamically stable final state. The resulting equilibrium shapes possess the full structural details expected for solids with weakly anisotropic surface free energies (in these cases, similar to 5% radial flattening and rounded [111] octahedral faces). The simplifying assumption of sphericity and perfect isotropy leads to an effective interfacial free energy as appearing in the Gibbs-Thomson equation, which we determine to be similar to 177 erg/cm(2), roughly independent of crystal size for radii in the 50-250 angstrom range. This quantity may be used in atomistically informed models of solidification kinetics for this system. Published by AIP Publishing.