Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unwinding of circular helicoidal molecules versus size   The thermodynamical stability of a set of circular double helical molecules
is analyzed by path integral techniques. The minicircles differ only in
\textit{i)} the radius and \textit{ii)} the number of base pairs ($N$) arranged
along the molecule axis. Instead, the rise distance is kept constant. For any
molecule size, the computational method simulates a broad ensemble of possible
helicoidal configurations while the partition function is a sum over the path
trajectories describing the base pair fluctuational states. The stablest
helical repeat of every minicircle is determined by free energy minimization.
We find that, for molecules with $N$ larger than $100$, the helical repeat
grows linearly with the size and the twist number is constant. On the other
hand, by reducing the size below $100$ base pairs, the double helices sharply
unwind and the twist number drops to one for $N=\,20$. This is predicted as the
minimum size for the existence of helicoidal molecules in the closed form. The
helix unwinding appears as a strategy to release the bending stress associated
to the circularization of the molecules.

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The categories of this paper are: hep-th
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The categories of this paper are: eess
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
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The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex