Effect of Bending Rigidity on the Knotting of a Polymer under Tension.

A coarse-grained computational model is used to investigate how the bending rigidity of a polymer under tension affects the formation of a trefoil knot. Thermodynamic integration techniques are applied to demonstrate that the free-energy cost of forming a knot has a minimum at nonzero bending rigidity. The position of the minimum exhibits a power-law dependence on the applied tension. For knotted polymers with nonuniform bending rigidity, the knots preferentially localize in the region with a bending rigidity that minimizes the free energy.