Secondary-structure phase formation for semiflexible polymers by bifurcation in hyperphase space

Canonical analysis has long been the primary analysis method for studies of phase transitions. However, this approach is not sensitive enough if transition signals are too close in temperature space. The recently introduced generalized microcanonical inflection-point analysis method not only enables the systematic identification and classification of transitions in systems of any size, but it can also distinguish transitions that standard canonical analysis cannot resolve. By applying this method to a generic coarse-grained model for semiflexible polymers, we identify a mixed structural phase dominated by secondary structures such as hairpins and loops that originates from a bifurcation in the hyperspace spanned by inverse temperature and bending stiffness. This intermediate phase, which is embraced by the well-known random-coil and toroidal phases, is testimony to the necessity of balancing entropic variability and energetic stability in functional macromolecules under physiological conditions. The bifurcation of the collapse transition line creates a stable phase of secondary loop and hairpin structures in the hyperphase diagram of semiflexible polymers.

Automated summary

The recently introduced generalized microcanonical inflection-point analysis method can systematically identify and classify transitions in systems of any size, as well as distinguish transitions that standard canonical analysis cannot resolve. By applying this method to a generic coarse-grained model for semiflexible polymers, researchers have identified a mixed structural phase dominated by secondary structures such as hairpins and loops, which originates from a bifurcation in the hyperspace spanned by inverse temperature and bending stiffness. This intermediate phase highlights the importance of balancing entropic variability and energetic stability in functional macromolecules under physiological conditions.