The structure factor and dynamics of the helix-coil transition

Thermodynamical properties of the helix-coil transition were successfully described in the past by the model of Lifson, Poland and Sheraga. Here we compute the corresponding structure factor and show that it possesses a universal scaling behaviour near the transition point, even when the transition is of first order. Moreover, we introduce a dynamical version of this model, that we solve numerically. A Langevin equation is also proposed, to describe the dynamics of the density of hydrogen bonds. Analytical solution of this equation shows dynamical scaling near the critical temperature and predicts a gelation phenomenon above the critical temperature. In the case when comparison of the two dynamical approaches is possible, the predictions of our phenomenological theory agree with the results of the Monte Carlo simulations.