RADIAL DEFORMATION OF CARBON NANOTUBES BY VAN-DER-WAALS FORCES

THE discovery of carbon nanotubes1,2 has stimulated many theoretical s tudies of their physical properties3-12, and their bulk synthesis13 sh ould soon make possible experimental measurements of these properties1 4. All studies so far have assumed that the nanotubes have perfect cyl indrical symmetry. Here we show that van der Waals forces between adja cent nanotubes can deform them substantially, destroying this cylindri cal symmetry. We present transmission electron microscopy images of tw o adjacent aligned tubes, about 100 angstrom in diameter, which show f lattening of the tubes along the contact region. Calculations on two-l ayer nested nanotubes indicate that these deformations can be explaine d on the basis of van der Waals interactions. We predict that these ef fects should be observable at least for tubes as small as 20 angstrom in diameter, and suggest that they may have a significant influence on the tubes' physical properties.