  For the first time, an approach is suggested for the quantitative description
of the electronic structure of single-walled carbon nanotubes and the
prediction of active sites for the tube controlled functionalization in view of
the tube length and ends structure. The approach is based on the tube
characteristic feature connected with odd electrons and is illustrated for a
family involving fragments of arm-chair configured (4,4) single-walled
nanotubes differing by length and end structure. Short and long tubes as well
as tubes with cap end and open end, in the latter case, both hydrogen
terminated and empty, are considered. Algorithms of the quantitative
description of the tubes of any length are suggested. Calculations were
performed in the framework of the single-determinant unrestricted Hartree-Fock
approach.
