Eur. Phys. J. B 29, 129-134 (2002)
https://doi.org/10.1140/epjb/e2002-00270-2

A simple model of DNA denaturation and mutually avoiding walks statistics

¹ INFM - Dipartimento di Fisica, Università di Padova, I-35131 Padova, Italy
² Theoretische Physik, Universität des Saarlandes, 66041 Saarbrücken, Germany

Corresponding author: ^a carlon@lusi.uni-sb.de

Received: 8 July 2002
Revised: 25 July 2002
Published online: 17 September 2002

Abstract

Recently Garel, Monthus and Orland [Europhys. Lett. 55, 132 (2001)] considered a model of DNA denaturation in which excluded volume effects within each strand are neglected, while mutual avoidance is included. Using an approximate scheme they found a first order denaturation. We show that a first order transition for this model follows from exact results for the statistics of two mutually avoiding random walks, whose reunion exponent is c > 2, both in two and three dimensions. Analytical estimates of c due to the interactions with other denaturated loops, as well as numerical calculations, indicate that the transition is even sharper than in models where excluded volume effects are fully incorporated. The probability distribution of distances between homologous base pairs decays as a power law at the transition.