Simple model for the DNA denaturation transition
Abstract
We study pairs of interacting selfavoiding walks \{ω^{1},ω^{2}\} on the 3d simple cubic lattice. They have a common origin ω^{1}_{0}=ω^{2}_{0}, and are allowed to overlap only at the same monomer position along the chain: ω^{1}_{i}≠ω^{2}_{j} for i≠j, while ω^{1}_{i}=ω^{2}_{i} is allowed. The latter overlaps are indeed favored by an energetic gain ɛ. This is inspired by a model introduced long ago by Poland and Sheraga [J. Chem. Phys. 45, 1464 (1966)] for the denaturation transition in DNA where, however, self avoidance was not fully taken into account. For both models, there exists a temperature T_{m} above which the entropic advantage to open up overcomes the energy gained by forming tightly bound twostranded structures. Numerical simulations of our model indicate that the transition is of first order (the energy density is discontinuous), but the analog of the surface tension vanishes and the scaling laws near the transition point are exactly those of a secondorder transition with crossover exponent φ=1. Numerical and exact analytic results show that the transition is second order in modified models where the selfavoidance is partially or completely neglected.
 Publication:

Physical Review E
 Pub Date:
 September 2000
 DOI:
 10.1103/PhysRevE.62.3958
 arXiv:
 arXiv:condmat/9910188
 Bibcode:
 2000PhRvE..62.3958C
 Keywords:

 87.15.Aa;
 64.60.Kw;
 Theory and modeling;
 computer simulation;
 Multicritical points;
 Condensed Matter  Soft Condensed Matter;
 Quantitative Biology
 EPrint:
 29 pages, LaTeX, 20 postscript figures