The Viscous and External Forces Effect on the Thermal Denaturation of Peyrard-Bishop Model

The breaking up of double helix into single helix DNA is called the DNA denaturation or thermal DNA melting. Theoretically, the phenomenon has been discussed in many works, for instance the work by Hanke et al. on the denaturation of stretched DNA. The opening double-stranded DNA canbe explained by a force exceeding a certain critical value. It is possible that the local opening of DNA bubbles in the selective regions without breaking the whole DNA. In other cases, the denaturation can also be influenced by many factor such as the alkaline compound filling up a cell, liquid surrounding DNA and other external potential. It has been shown that a bell shaped soliton exists in the DNA chain when the effect of viscosity is taken into account. 

The melting temperature as well as the critical force that is required to unzip the DNA molecule depend on the salt concentration of the solution.One of the physical model that have been discussed by researchers is called the Peyrard-Bishop (PB) model. This model basicallyconsiders the DNA as two mutually hand in chains with the Morse as theinteraction potential. The model can explain the denaturation process along with its thermodynamical properties.