Self-replicating twins in nanowires.

Based on molecular-dynamics simulations validated with quantum-mechanical calculations, we predict that (111) twin planes in a [111]-oriented GaAs nanowire attain attractive interactions mediated by surface strain. This gives rise to a self-replication mechanism that continuously generates a twin superlattice in a nanowire during growth. We demonstrate significant implications of the twin-twin interaction for the electronic, mechanical, and chemical properties of nanowires.

Embrittlement of metal by solute segregation-induced amorphization.

Impurities segregated to grain boundaries of a material essentially alter its fracture behavior. A prime example is sulfur segregation-induced embrittlement of nickel, where an observed relation between sulfur-induced amorphization of grain boundaries and embrittlement remains unexplained. Here, 48x10(6)-atom reactive-force-field molecular dynamics simulations provide the missing link.