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Order of the phase transition in models of DNA thermal denaturation

Nikos Theodorakopoulos, Thierry Dauxois, Michel Peyrard

cond-mat.stat-mecharXiv:cond-mat/0004487

Abstract

We examine the behavior of a model which describes the melting of double-stranded DNA chains. The model, with displacement-dependent stiffness constants and a Morse on-site potential, is analyzed numerically; depending on the stiffness parameter, it is shown to have either (i) a second-order transition with "nuperpendicular" = - beta = 1, "nuparallel" = gamma/2 = 2 (characteristic of short range attractive part of the Morse potential) or (ii) a first-order transition with finite melting entropy, discontinuous fraction of bound pairs, divergent correlation lengths, and critical exponents "nuperpendicular" = - beta = 1/2, "nuparallel" = gamma/2 = 1.

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