Atomistic simulation study of the structure and dynamics of a faceted crystal-melt interface

Abstract

A detailed analysis of the structure and dynamics of the crystal-melt interface region in silicon, modeled with the Stillinger-Weber potential, is performed via molecular dynamics simulations. The focus is on the faceted (111) crystal-melt interface, but properties of the rough (100) interface are also determined. We find an intrinsic 10-90 interface width of $0.681\ifmmode\pm\else\textpm\fi{}0.001\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ for the coarse-grained density profile at the (111) interface and a $0.570\ifmmode\pm\else\textpm\fi{}0.005\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ width at the (100) interface. Coarse-grained profiles of a suitably defined local order parameter are found to show a smaller width anisotropy between (111) and (100) interfaces while the order profiles exhibit a $0.20--0.25\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ shift in position toward the crystal phase relative to the corresponding density profiles. The structural analysis of the layer of melt adjacent to the (111) facet of the crystal finds ordered clusters with average lifetimes of $16\phantom{\rule{0.3em}{0ex}}\mathrm{ps}$, as determined from autocorrelations of time-dependent layer structure factors, and cluster radii of gyration from $0.2\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ for the smallest cells to as large as $1.5\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$.