Correlation of thermal stability with structural properties of ultrathin single-walled carbon nanotubes

Based on quantum chemical calculations, we have established the relationship between the thermal stability and structural properties of ultrathin single-walled carbon nanotubes (SWCNTs). Our results on the heat of formation as a function of tube diameter predict a lower limit of 0.341 nm in diameter for experimentally observable SWCNTs. The absence of any distinctive minimum points on the heat of formation curve implies the experimental difficulties in obtaining uniform tubes. A detailed correlation between their curvature and chemical bonding properties was obtained for both the zigzag and armchair conformations.