Curvature, hybridization, and STM images of carbon nanotubes

The curvature effects in carbon nanotubes are studied analytically as a function of chirality. The pi orbitals are found to be significantly rehybridized in all tubes, so that they are never normal to the tubes' surface. This results in a curvature induced gap in the electronic band structure, which turns out to be larger than previous estimates. The tilting of the pi orbitals should be observable by atomic resolution scanning tunneling microscopy measurements.