No cage, no tube: Relative stabilities of nanostructures

Abstract

Relative stabilities of nanostructures are important in the design and selection of components for nanodevices. Here, we use first-principles simulations to evaluate the relative stabilities of representative nanostructures of semimetal Bi, semiconductive C, and metallic Au. The Bincages are metastable and highly active and can readily transform to more stable three-dimensional amorphous structures upon activation. Both finite bismuth nanotubes and infinite nanotubes are even less stable than the cage structures. This is contrary to the cases for carbon, boron, and gold. The differences lie in their bonding characteristics and their responses to curvature. Our findings show tendencies of evolution of different types of nanostructures and also indicate that if a nanocage is (not) stable, then its nanotube is even more (less) stable. Hence, the stability of a cage structure predetermines the existence of a nanotube for a given element: i.e., no cage, no tube. © 2008 American Chemical Society.