Monte Carlo simulation of growth of hard-sphere crystals on a square pattern

Monte Carlo simulations of the colloidal epitaxy of hard spheres (HSs) on a square pattern have been performed. This is an extension of previous simulations; we observed a shrinking intrinsic stacking fault running in an oblique direction through the glide of a Shockley partial dislocation terminating its lower end in fcc (0 0 1) stacking [A. Mori, Y. Suzuki, S.i. Yanagiya, T. Sawada, K. Ito, Mol. Phys. 105 (2007) 1377], which was an answer to a question why the defect in colloidal crystals reduced by gravity [J. Zhu, M. Li, R. Rogers, W. Meyer, R. Ottewill, W. Russel, P.M. Chaikin, STS-73 Space Shuttle Crew. Nature 387 (1997) 883]. We have resolved one of the shortcomings of the previous simulations; the driving force for fcc (0 0 1) stacking, which was a stress from a small periodic boundary simulation box, has been replaced with the stress from a pattern on the bottom. We have observed disappearance of stacking fault in this realizable condition. Sinking of the center of gravity has been smooth and of a single relaxation mode under the condition that the gravitational energy mgσ is slightly less than the thermal energy kBT. In the snapshots tetrahedral structures have appeared often, suggesting formation of staking fault tetrahedra.