Heterogeneous crystallization of hard spheres on patterned substrates.

We report a numerical investigation of the crystallization of monodisperse hard spheres on different patterned substrates. We find that the duration of a metastable fluid state, which may last for relatively long time in the homogeneous crystallization, can be deeply reduced or almost eliminated when a substrate is used as the seed of crystallization. In the presence of the square patterned substrate, which has the basic character of the body-centered cubic (bcc) crystal structure, a transient bcc crystal phase was observed, suggesting that the bcc structure could be possible to be stabilized by the square patterned substrates. The process of crystallization becomes complicated when the patterned substrate is incommensurate with the bulk crystal. Furthermore, a purely face-centered cubic or hexagonal close packed crystal phase with stacking faults can be generated by using a certain patterned substrate without other factors such as gravity.