Force-Induced Melting and Thermal Melting of a Double-Stranded Biopolymer

As a prototype of systems bearing a localization-delocalization transition, the strand-separation (melting) process in a double-stranded biopolymer is studied by a mapping to a quantum-mechanical problem with short-ranged potentials. Both the bounded and the extensive eigenmodes of the corresponding Schrodinger equation are considered and exact expressions for the configurational partition function and free energy are obtained. The force-induced melting is a first order phase transition process, while the thermal melting is found to be second order. Some scaling exponents governing thermal melting are given.