Polyelectrolyte Threading through a Nanopore

Threading charged polymers through a nanopore, driven by electric fields E, is investigated by means of Langevin dynamics simulations. The mean translocation time [Formula: see text] is shown to follow a scaling law [Formula: see text] , and the exponent α increases monotonically from [Formula: see text] to [Formula: see text] with E. The result is double-checked by the calculation of mean square displacement of translocation coordinate, which asserts a scaling behavior [Formula: see text] (for t near τ) with β complying with the relation [Formula: see text]. At a fixed chain length N, [Formula: see text] displayed a reciprocal scaling behavior [Formula: see text] in the weak and also in the strong fields, connected by a transition [Formula: see text] in the intermediate fields. The variations of the radius of gyration of chain and the positions of chain end are monitored during a translocation process; far-from-equilibrium behaviors are observed when the driving field is strong. A strong field can strip off the condensed ions on the chain when it passes the pore. The total charges of condensed ions are hence decreased. The studies for the probability and density distributions reveal that the monomers in the trans-region are gathered near the wall and form a pancake-like density profile with a hump cloud over it in the strong fields, due to fast translocation.