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.