Wall-induced prefreezing in hard spheres: A thermodynamic perspective

Using our cleaving-wall method developed previously for the study of crystal-melt interfaces (J. Phys. Chem. B 2005, 109, 17802), we compute with high precision the interfacial free energies of the hard-sphere fluid. d (gamma,(wf)) and crystal (gamma,,) in contact with a structureless hard wall. The interfacial free energies are determined as functions of density and, for gamma(wc),c, as functions of crystal/wall orientation [(111), (100), and (110)]. Using the current calculations, along with our previously calculated value for the hard-sphere (111) crystal-fluid interfacial free energy, gamma(111)(cf) , we show that, at the crystal-fluid coexistence conditions, yw gamma(wf)- [gamma(111)(wc) + gamma(111)(cf)] > 0. This inequality demonstrates that a (111) hard-sphere crystal will completely wet a hard-sphere fluid/structureless hard wall. This conclusion from thermodynamics is consistent with recent structural evidence by Dijkstra (Phys. Rev. Lett. 2004, 93, 108303) of wall-induced prefreezing of a hard-sphere fluid in contact with a structureless hard wall. We also find evidence that a (111) crystal will wet a (110) crystal/wall interface.