Where is the Odijk back-folding regime when a self-excluding wormlike polymer is confined by a cylindrical tube?

When a semiflexible chain is confined in a cylindrical tube, it forms hairpin loops back and forth inside the confining tube. The multi-threads of polymer segments in the narrow tube crosssection impose the excluded-volume interactions among the folded chain segments. Recent theories and Monte Carlo simulations have explored the scaling properties of the chain extension and confinement free energy caused by both confinement and excluded-volume effects. In particular, an Odijk scaling regime, distinguished from the extended de Gennes regime, is expected when the tube diameter is smaller than the persistence length. Here, the excluded-volume effects are added to
the standard wormlike-chain model by a self-consistent field theory. The theory gives rise to a unified linear-response regime where it contains both Odijk and extended de~Gennes regimes. Through solving the probability functions numerically in high precision, the further division of the linear-response regime into these scaling regimes is critically examined.