Renormalisation group determination of the order of the DNA denaturation transition

We report on the nature of the thermal denaturation transition of homogeneous DNA as determined from a renormalisation group analysis of the Peyrard-Bishop-Dauxois model. Our approach is based on an analogy with the phenomenon of critical wetting that goes further than previous qualitative comparisons, and shows that the transition is continuous for the average base-pair separation. However, since the range of universal critical behaviour appears to be very narrow, numerically observed denaturation transitions may look first-order, as it has been reported in the literature.

💡 Research Summary

The paper tackles a long‑standing controversy in biophysics: whether the thermal denaturation (melting) of homogeneous DNA proceeds via a first‑order (discontinuous) or a second‑order (continuous) phase transition. To answer this, the authors revisit the Peyrard‑Bishop‑Dauxois (PBD) model, which describes each base‑pair by a single coordinate (y_i) representing the separation of the two strands. The model contains a nonlinear on‑site Morse potential (V(y)=D