Crystal-melt interface stresses: atomistic simulation calculations for a Lennard-Jones binary alloy, Stillinger-Weber Si, and embedded atom method Ni.

Molecular-dynamics and Monte Carlo simulations have been used to compute the crystal-melt interface stress (f) in a model Lennard-Jones (LJ) binary alloy system, as well as for elemental Si and Ni modeled by many-body Stillinger-Weber and embedded-atom-method (EAM) potentials, respectively. For the LJ alloys the interface stress in the (100) orientation was found to be negative and the f vs composition behavior exhibits a slight negative deviation from linearity. For Stillinger-Weber Si, a positive interface stress was found for both (100) and (111) interfaces: f{100}=(380+/-30)mJ/m{2} and f{111}=(300+/-10)mJ/m{2}. The Si (100) and (111) interface stresses are roughly 80 and 65% of the value of the interfacial free energy (gamma) , respectively. In EAM Ni we obtained f{100}=(22+/-74)mJ/m{2}, which is an order of magnitude lower than gamma. A qualitative explanation for the trends in f is discussed.

Size-dependent nucleation kinetics at nonplanar nanowire growth interfaces.

In nanowire growth, kinetic processes at the growth interface can play an important role in governing wire compositions, morphologies, and growth rates. Molecular-dynamics simulations have been undertaken to probe such processes in a system featuring a solid-liquid interface shape characterized by a facet bounded by rough orientations. Simulated growth rates display a dependence on nanowire diameter consistent with a size-dependent barrier for facet nucleation. A theory for the interface mobility is developed, establishing a source for size-dependent growth rates that is an intrinsic feature of systems possessing growth interfaces with faceted and rough orientations.