First-order phase transition in a stiff polymer chain

We studied the transition between the elongated coil and collapsed globule states in a single polymer chain, avoiding kinetic effects such as supercooling, or kinetic trapping into local minima, using a multicanonical method. It has become clear that single stiff chains exhibits a first-order phase transition. Reflecting the finiteness of the number of elements (or the number of segments) in a chain, the two states, coil and globule, coexist within a finite width of temperature for the ensemble of monodisperse chains, even under true thermodynamic equilibrium.