Polymer translocation through a nanopore: A two-dimensional Monte Carlo study

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Abstract
We investigate the problem of polymer translocation through a nanopore in the absence of an external driving force. To this end, we use the two-dimensional fluctuating bond model with single-segment Monte Carlo moves. To overcome the entropic barrier without artificial restrictions, we consider a polymer which is initially placed in the middle of the pore and study the escape time τ required for the polymer to completely exit the pore on either end. We find numerically that τ scales with the chain length N as τ∼N1+2ν, where ν is the Flory exponent. This is the same scaling as predicted for the translocation time of a polymer which passes through the nanopore in one direction only. We examine the interplay between the pore length L and the radius of gyration Rg. For L⪡Rg, we numerically verify that asymptotically τ∼N1+2ν. For L⪢Rg, we find τ∼N. In addition, we numerically find the scaling function describing crossover between short and long pores. We also show that τ has a minimum as a function of L for longer chains when the radius of gyration along the pore direction R‖≈L. Finally, we demonstrate that the stiffness of the polymer does not change the scaling behavior of translocation dynamics for single-segment dynamics.
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