Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: First-principles calculation of electronic polarization of III-V
  nanotubes   A first-principles study of the electronic polarization of BN and AlN
nanotubes and their graphitic sheets under an external electric field has been
performed. We found that the polarization per atom of zigzag nanotubes
increases with decreasing diameter while that of armchair nanotubes decreases.
The variation of the polarization is related to the exterior angle of the bonds
around the B or Al atoms rather than that around the N atoms. The increase in
the polarization of the zigzag nanotubes with decreasing diameter is caused by
the large variation of the exterior angle when they are wrapped into the
tubular form. On the other hand, the decrease in the bond length results in the
weak polarization of thin armchair nanotubes.

8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
22
The categories of this paper are: chao-dyn
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph