The electron structures of two forms of the grafted carbon dimer for the (8, 0) zigzag nanotube were calculated by the semiempirical quantumchemistry method applied to the supercell model. If the dimer adsorbs above the center of the tube’s hexagon (hgrafting), it performs the topochemical transformation of the tube, according to the Stone–Wales scheme of inverse kind. Bgrafting is a chemisorption above tube’s bond, it is energetically lower, than hgrafting. Atomic structure of bgrafting is a splitted diinterstitial. Measuring the electronic density of states in the upper valence bandhas been shown to make it possible to distinguish between pure and grafted nanotubes, as well as between band hgraftings.