ELECTRONIC-STRUCTURE OF SINGLE-WALL, MULTIWALL, AND FILLED CARBON NANOTUBES

We determine the electronic structure of single-wall, multiwall, and f illed carbon nanotubes using the local-density-functional formalism. I n order to handle these extremely inhomogeneous systems of nested grap hene cylinders with 10(3)-10(4) valence electrons, we adopt a techniqu e that discretizes the eigenvalue problem on a grid and yields simulta neously all occupied and unoccupied states. We apply this formalism to nanotubes, where the ionic background can be described by infinitely thin structureless cylindrical walls, and the electron distribution is subsequently obtained in a self-consistent manner. Comparison with pa rametrized calculations, which consider explicitly the atomic position s, proves that the essential features of the electronic structure in t hese systems do not depend on the exact atomic positions.