  The dynamics of the DNA denaturation is studied using the
Peyrard-Bishop-Dauxois model. The denaturation rate of double stranded polymers
decreases exponentially as function of length below the denaturation
temperature. Above Tc, the rate shows a minimum, but then increases as function
of length. We also examine the influence of sequence and solvent friction.
Molecules having the same number of weak and strong base-pairs can have
significantly different opening rates depending on the order of base-pairs.
