Acoustic and optical soliton excitations in the Peyrard-Bishop model of DNA dynamics with alternating A-T and G-C base pairs

With an attempt to describe DNA dynamics in a more realistic way, we introduce an extended Peyrard-Bishop (PB) model which takes into account the possible alternation between AT and GC pairs. The out-of-phase motion is then described by a set of coupled discrete differential equations which implies the existence of optical and acoustic modes. Through the semi-discrete approximation, a complex Ginzburg-Landau (CGL) equation describes the dynamics of the base pairs. It is shown that, the more probable DNA dynamics occurs the optical mode, since it has a deep influence in energy exchange and collision phenomena.