Direct Calculation of the Hard-Sphere Crystal/Melt Interfacial Free Energy

We present a direct calculation by molecular-dynamics computer simulation of the crystal/melt interfacial free energy $\gamma$ for a system of hard spheres of diameter $\sigma$. The calculation is performed by thermodynamic integration along a reversible path defined by cleaving, using specially constructed movable hard-sphere walls, separate bulk crystal, and fluid systems, which are then merged to form an interface. We find the interfacial free energy to be slightly anisotropic with $\gamma =0.62\mathrm{}\pm 0.01$, $0.64\pm 0.01$, and $0.58\pm {0.01k}_{B}T/{\sigma }^2$ for the (100), (110), and (111) fcc crystal/fluid interfaces, respectively. These values are consistent with earlier density functional calculations and recent experiments.