Speaker
Prof.
Tapio Ala-Nissilä
(Aalto University School of Science, Espoo and Brown University, Providence, Rhode Island)
Description
We present a Brownian dynamics model of driven polymer
translocation, in which non-equilibrium memory effects
arising from tension propagation (TP) along the cis side
subchain are incorporated as a time-dependent friction. To
solve the effective friction, we develop a finite chain
length TP formalism, based on the idea suggested by Sakaue
[Sakaue, PRE 76, 021803 (2007)]. We validate the model by
numerical comparisons with high-accuracy molecular dynamics
simulations, showing excellent agreement in a wide range of
parameters. Our results show that the dynamics of driven
translocation is dominated by the non-equilibrium TP along
the cis side subchain. Furthermore, by solving the model for
chain lengths up to 10^10 monomers, we show that the chain
lengths probed by experiments and simulations are typically
orders of magnitude below the asymptotic scaling limit. This
explains both the considerable scatter in the observed
scaling of translocation time w.r.t. chain length, and some
of the shortcomings of other present theories. Our study
shows that for a quantitative theory of polymer
translocation, explicit consideration of finite chain
length effects is required.
