Driven polymer translocation through nanopores: slow versus fast dynamics

TL;DR

This study uses 3D Langevin Dynamics simulations to analyze how polymer translocation times scale with polymer length and driving force, revealing different behaviors in slow versus fast translocation regimes.

Contribution

It provides a detailed comparison of translocation dynamics under varying forces, clarifying the scaling exponents and non-equilibrium effects involved.

Findings

Slow translocation scaling exponent ≈ 1.588

Fast translocation scaling exponent ≈ 1.37

Translocation time scales inversely with force, with different exponents

Abstract

We investigate the dynamics of polymer translocation through nanopores under external driving by 3D Langevin Dynamics simulations, focusing on the scaling of the average translocation time $\tau$ versus the length of the polymer, $\tau\sim N^{\alpha}$. For slow translocation, i.e., under low driving force and/or high friction, we find $\alpha \approx 1+\nu \approx 1.588$ where $\nu$ denotes the Flory exponent. In contrast, $\alpha\approx 1.37$ is observed for fast translocation due to the highly deformed chain conformation on the trans side, reflecting a pronounced non-equilibrium situation. The dependence of the translocation time on the driving force is given by $\tau \sim F^{-1}$ and $\tau \sim F^{-0.80}$ for slow and fast translocation, respectively. These results clarify the controversy on the magnitude of the scaling exponent $\alpha$ for driven translocation.