Direct calculation of the crystal–melt interfacial free energies for continuous potentials: Application to the Lennard-Jones system

Ruslan L Davidchack,Brian B Laird

doi:10.1063/1.1563248

Abstract

Extending to continuous potentials a cleaving wall molecular dynamics simulation method recently developed for the hard-sphere system [Phys. Rev. Lett. 85, 4751 (2000)], we calculate the crystal–melt interfacial free energies, γ, for a Lennard-Jones system as functions of both crystal orientation and temperature. At the triple point, T*=0.617, the results are consistent with an earlier cleaving potential calculation by Broughton and Gilmer [J. Chem. Phys. 84, 5759 (1986)], however, the greater precision of the current calculation allows us to accurately determine the anisotropy of γ. From our data we find that, at all temperatures studied, γ111&lt;γ110&lt;γ100. A comparison is made to the results from our previous hard-sphere calculation and to recent results for Ni by Asta, Hoyt, and Karma [Phys. Rev. B 66 100101(R) (2002)].

Highlights

The magnitude and orientational dependenceanisotropyof the solid–liquid interfacial free energy, ␥, is a primary controlling parameter in the kinetics and morphology of crystal growth from the melt,[1] especially in the case of dendritic growth.[2]
Usually involving contact angle studies, are quite difficult and relatively few in number,[5] and, with the exception of a small number of studies on transparent organic materials,[6,7] are not of sufficient precision to resolve anisotropy. This paucity of reliable direct experimental measurements on technologically useful materialssuch as metalshas motivated the development of a variety of novel computational methods to determine ␥ via molecular simulation.[8,9,10,11]
We extend our cleaving wall approach to systems of particles interacting with continuous potentials, applying it to the system of truncated LJ particles considered by Broughton and Gilmer