Computational Materials Science Center: PUBLICATIONS

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 cluster, 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 temperature and size ranges. The average surface energy af an atom was found to be independent of cluster size and of magnitude relative to the bulk, such that all cluster sizes were stable under the conditions studied here (600 < T < 2000 K). The phonon density of states is similar to bulk silicon and does not show a strong cluster size dependence. Atomic self-difussion coefficients have been calculated and compare quite well with experimental data on self difussion coefficient measurments of silicon surfaces.

Click on Image to Enlarge Time evolution of a coalescing silicon cluster shown along with its internal temperature and moment of inertia plotted vs. time. An initial sharp increase in temperature immediately follows the collision, after which a gradual temperature rise characteristic of the neck disappearance. The subsequent reshaping from oval to spherical takes considerably longer times and occurs without temperature increases.