Bubble coalescence in interacting system of DNA molecules

We consider two models of interacting DNA molecules: First is (four parametric) bubble coalescence model in interacting DNAs (shortly: BCI-DNA). Second is (three parametric) bubble coalescence model in a condensed DNA molecules (shortly BCC-DNA). To study bubble coalescence thermodynamics of BCI-DNA and BCC-DNA models we use methods of statistical physics. Namely, we define Hamiltonian of each model and give their translation-invariant Gibbs measures (TIGMs). For the first model, we find parameters such that corresponding Hamiltonian has up to three TIGMs (three phases of system) biologically meaning existence of three states: "No bubble coalescence", "Dominated soft zone", "Bubble coalescence". For the second model, we show that for any (admissible) parameters, this model has unique TIGM. This is a state where "No bubble coalescence" phase dominates.