Properties of Silicon Nanoparticles: A Molecular Dynamics Study

Abstract

Constant energy molecular dynamics simulations of silicon cluster growth have been conducted for clusters up to 480 atoms using the Stillinger−Weber empirical interatomic potential. It is found that the interior atoms of the 480-atom clusters, at the temperatures used, show bulklike characteristics. The cluster binding energy has been fit to an expression that separates the surface and bulk contributions to the energy over wide temperatures and size ranges. The average surface energy of an atom was found to be independent of cluster size and of a magnitude relative to the bulk, such that all cluster sizes were stable under the conditions studied here (600 < T < 2000 K). The photon density of states is similar to bulk silicon and does not show a strong cluster size dependence. Atomic self-diffusion coefficients have been calculated and compare quite well with experimental data on self-diffusion coefficient measurements of silicon surfaces.