The thermal denaturation of the Peyrard-Bishop model with an external potential

The impact of various types of external potentials on the Peyrard-Bishop DNA denaturation is investigated through the statistical mechanics approach. The partition function is obtained using the transfer integral method, and the stretching of hydrogen bonds is calculated using the time-independent perturbation method. It is shown that all types of external potentials accelerate the denaturation processes at lower temperature. In particular, it is argued that the Gaussian potential with infinitesimal width reproduces a constant force at one end of the DNA sequence as was already done in some previous works. (paper)