Stretching of a polymer below the theta point.
The unfolding of a polymer below the theta point when pulled by an external force is studied both in d=2 on the lattice and in d=3 off the lattice. At T=0 and for finite length chains, it is found that the globule unfolds via multiple steps, corresponding to transitions between different minima, in both cases. In d=3 one of these intermediates is a regular helix. In the infinite length limit, these steps have a qualitative effect only in d=2. The phase diagram in d=2 is determined via the transfer matrix. To rationalize these results, energy-entropy and renormalization group arguments are given.
Marenduzzo
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International School for Advanced Studies (SISSA) and INFM, Via Beirut 2-4, 34014 Trieste, Italy.
Maritan
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Rosa
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Seno
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D001704:Biopolymers / Q000737:chemistry*; D004247:DNA / Q000737:chemistry; D008956:Models, Chemical; D009690:Nucleic Acid Conformation; D017510:Protein Folding; D013314:Stress, Mechanical; D013696:Temperature
D001704:Biopolymers; D004247:DNA