Helicoidal model for DNA opening

We present a new dynamical model of DNA. This model has two degrees of freedom per base-pair: one radial variable related to the opening of the hydrogen bonds and an angular one related to the twisting of each base-pair responsible for the helicoidal structure of the molecule. The small amplitude dynamics of the model is studied analytically : we derive small amplitude envelope solutions made of a breather in the radial variables combined with a kink in the angular variables, showing the role of the topological constraints associated to the helicoidal geometry. We check the stability of the solutions by numerical integration of the motion equations.