Model structure of perfectly graphitizable coiled carbon nanotubes

The connection of two straight chiral or achiral cylindrical carbon nanotube sections of approximately the same diameters connecting at a ''knee'' angle of pi/5 is described. Such knees are based on the insertion in the plane of the knee of diametrically opposed pentagonal and heptagonal rings in the hexagonal network. Relationships are also established between the nanotubes and their concentric graphitic layers. A growth mechanism leading to perfect carbon tubules and tubule connections on a catalyst particle at a molecular level is described. The mechanism suggested explains the formation of curved nanotubes, tori or coils involving the heptagon-pentagon construction of Dunlap.