Mechanical unfolding of directed polymers in a poor solvent: critical exponents.
We study the thermodynamics of an exactly solvable model of a self-interacting, partially directed self-avoiding walk in two dimensions when a force is applied on one end of the chain. The critical force for the unfolding is determined exactly, as a function of the temperature, below the Theta transition. The transition is of second order and is characterized by new critical exponents that are determined by a careful numerical analysis. The usual polymer critical index nu on the critical line, and another one which we call zeta, takes a nontrivial value that is numerically close to 2/3.
Rosa
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International School for Advanced Studies (SISSA) and INFM, Via Beirut 2-4, 34014 Trieste, Italy.
Marenduzzo
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Maritan
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Seno
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