Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why do nanotubes grow chiral?   Carbon nanotubes (CNT) hold enormous technological promise. It can only be
harnessed if one controls in a practical way the CNT chirality, the feature of
the tubular carbon topology that governs all the CNT properties---electronic,
optical, mechanical. Experiments in catalytic growth over the last decade have
repeatedly revealed a puzzling strong preference towards minimally-chiral
(near-armchair) CNT, challenging any existing hypotheses and turning chirality
control ever more tantalizing yet leaving its understanding elusive. Here we
combine the CNT/catalyst interface thermodynamics with the kinetic growth
theory to show that the unusual near-armchair peaks emerge from the two
antagonistic trends: energetic preference towards achiral CNT/catalyst
interfaces vs. faster growth of chiral CNT. This narrow distribution is
profoundly related with the peaked behavior of a simple function, x*exp(-x).

23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg