First-order disorder-to-order transition in an isolated homopolymer model

The thermodynamic behavior of an isolated freely jointed homonuclear square-well 64mer chain is studied by discontinuous molecular dynamics simulations. It is shown that there are three transitions that can be described as gas-liquid, liquid-solid, and solid-solid polymorphic transitions. The liquid-solid-like transition is a first-order (two-state) disorder-to-order transition. Implications of the results for protein folding are briefly discussed.