Inhomogeneous Charge Distributions Copolymers and Pinning

We introduce inhomogeneities in the polymer chain, or at the interface or defect line, by assigning to each monomer, or to each interface site, a charge, that is a real number that will determine quantitatively the interaction of the chain with the surrounding environment. For example, an inhomogeneous pinning model is the following  

With a binary choice of the values of o , that is u n a, b, a b, corresponding to the interaction energies of A-T and C-G couples, in view of the discussion in Section 1.4, P, w,/3 inhomogeneous Poland-Scheraga model, which gives a more realistic model for the DNA denaturation transition (we will come back to this issue in Section 1.10 and in Section 5.7). 

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