Non-Markovian closure kinetics of flexible polymers with hydrodynamic interactions

This paper presents a theoretical analysis of the closure kinetics of a polymer with hydrodynamic interactions. This analysis, which takes into account the non-Markovian dynamics of the end-to-end vector and relies on the preaveraging of the mobility tensor (Zimm dynamics), is shown to reproduce very accurately the results of numerical simulations of the complete non linear dynamics. It is found that Markovian treatments, based on a Wilemski-Fixman approximation, significantly overestimate cyclization times (up to a factor 2), showing the importance of memory effects in the dynamics. In addition, this analysis provides scaling laws of the mean first cyclization time (MFCT) with the polymer size $N$ and capture radius $b$, which are identical in both Markovian and non-Markovian approaches. In particular, it is found that the scaling of the MFCT for large $N$ is given by $T\sim N^{3/2}\ln (N/b^2)$, which differs from the case of the Rouse dynamics where $T\sim N^{2}$. The extension to the case of the reaction kinetics of a monomer of a Zimm polymer with an external target in a confined volume is also presented.

Nicolas Levernier, Maxim Dolgushev, Olivier Bénichou, Alexander Blumen, Thomas Guérin, Raphaël Voituriez · 2017