Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fermi level quantum numbers and secondary gap of conducting carbon
  nanotubes   For the single-wall carbon nanotubes conducting in the simplest tight binding
model, the complete set of line group symmetry based quantum numbers for the
bands crossing at Fermi level are given. Besides linear (k), helical (k'} and
angular momenta, emerging from roto-translational symmetries, the parities of U
axis and (in the zig-zag and armchair cases only) mirror planes appear in the
assignation. The helical and angular momentum quantum numbers of the crossing
bands never vanishes, what supports proposed chirality of currents. Except for
the armchair tubes, the crossing bands have the same quantum numbers and,
according to the non-crossing rule, a secondary gap arises, as it is shown by
the accurate tight-binding calculation. In the armchair case the different
vertical mirror parity of the crossing bands provides substantial conductivity,
though kF is slightly decreased.

8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
17
The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci