Polymer translocation through a nanopore under a pulling force.

We investigate polymer translocation through a nanopore under a pulling force using Langevin dynamics simulations. We concentrate on the influence of the chain length N and the pulling force F on the translocation time tau . The distribution of tau is symmetric and narrow for strong F . We find that tau approximately N{2} and translocation velocity v approximately N{-1} for both moderate and strong F . For infinitely wide pores, three regimes are observed for tau as a function of F . With increasing F , tau is independent of F for weak F , and then tau approximately F{-2+nu{-1}} for moderate F, where nu is the Flory exponent, which finally crosses over to tau approximately F{-1} for strong force. For narrow pores, even for moderate force tau approximately F{-1}. Finally, the waiting time, for monomer s and monomer s+1 to exit the pore, has a maximum for s close to the end of the chain, in contrast to the case where the polymer is driven by an external force within the pore.