On the disordered SAW model for DNA denaturation

Abstract

We investigate numerically the transition properties for models of DNA denaturation, which can be relevant for certain classes of disordered systems. The investigation follows two, complementary, numerical approaches: on-lattice Monte Carlo like simulations or off-lattice statistical mechanics calculations, which can extend very significantly the affordable lengths for the sequences. The on-lattice model consists of two interacting self-avoiding walks with the same origin on a three-dimensional cubic lattice. We introduce two different contact energies, for the adenine–thymine coupling and the guanine–cytosine one, respectively, distributed according to a bimodal law. Whereas the transition is recognized to be of first order in the pure (homopolymer) case, the behaviour of quantities averaged over disorder suggests that the random system undergoes a second-order transition.