Diffusion-controlled first contact of the ends of a polymer: Crossover between two scaling regimes

We report on Monte Carlo simulations of loop formation of an ideal flexible polymer consisting of N bonds with two reactive ends. We determine the first-passage time associated with chain looping that yields a conformation in which the end monomers are separated by a distance a-the reaction radius. In particular, our numerical results demonstrate how this time scale crosses over from tau(first)similar to N-3/2/a to the a-independent tau(first)similar to N-2 as N is increased. The existence and characteristics, of the two scaling regimes and the crossover between the two, are further illuminated by a scaling argument.