A MODEL STUDY OF NARROW NANOTUBES RELATED TO C₃₆, C₃₂, C₂₀, AND C₁₆: SEMIEMPIRICAL AND NONEMPIRICAL TREATMENTS

ABSTRACT

Very recently, narrow nanotubes have been observed with diameters of 5 or even 4 Å. In this report we perform calculations of narrow model nanotubes capped by fragments of D _2d and D _6h C₃₆ fullerene cages or by fragments of C₃₂ and C₁₆ quasi-fullerene cages with two four-membered rings, or finally by a fragment of dodecahedral C₂₀. The computations can reproduce the observed diameters of the narrow nanotubes. The results also indicate that fragments of C₃₂, used as caps instead of C₃₆, can lead to quite competitive energetics. Thus, a novel possibility that some of the narrow nanotubes can contain four-membered rings at their tips is suggested.

ACKNOWLEDGMENTS

The reported research has been supported by the National Science Council, Taiwan, Republic of China. The authors also thank the National Center for High-Performance Computing in Hsinchu, Taiwan, Republic of China, and the Supercomputer Centers of Charles University, Prague, and Masaryk University, Brno, for computer time.