Direct calculation of the hard-sphere crystal/melt interfacial free energy

We present a direct calculation by molecular-dynamics computer simulation o f the crystal/melt interfacial free energy gamma for a system of hard spher es of diameter sigma. The calculation is performed by thermodynamic integra tion along a reversible path defined by cleaving, using specially construct ed movable hard-sphere walls, separate bulk crystal, and fluid systems, whi ch are then merged to form an interface. We find the interfacial free energ y to be slightly anisotropic with gamma = 0.62 +/- 0.01, 0.64 +/- 0.01, and 0.58 +/- 0.01 k(B)t/sigma (2) for the (100), (110), and (111) fee crystal/ fluid interfaces, respectively. These values are consistent with earlier de nsity functional calculations and recent experiments.