Uniform description of polymer ejection dynamics from capsid with and without hydrodynamics

J. Piili, P. M. Suhonen, and R. P. Linna
Phys. Rev. E 95, 052418 – Published 26 May 2017

Abstract

We use stochastic rotation dynamics (SRD) to examine the dynamics of the ejection of an initially strongly confined flexible polymer from a spherical capsid with and without hydrodynamics. The results obtained using stochastic rotation dynamics (SRD) are compared to similar Langevin simulations. Inclusion of hydrodynamic modes speeds up the ejection but also allows the part of the polymer outside the capsid to expand closer to equilibrium. This shows as higher values of radius of gyration when hydrodynamics are enabled. By examining the waiting times of individual polymer beads, we find that the waiting time tw grows with the number of ejected monomers s as a sum of two exponents. When 63% of the polymer has ejected, the ejection enters the regime of slower dynamics. The functional form of tw versus s is universal for all ejection processes starting from the same initial monomer densities. Inclusion of hydrodynamics only reduces its magnitude. Consequently, we define a universal scaling function h such that the cumulative waiting time t=N0h(s/N0) for large N0. Our unprecedentedly precise measurements of force indicate that this form for tw(s) originates from the corresponding force toward the pore decreasing superexponentially at the end of the ejection. Our measured tw(s) explains the apparent superlinear scaling of the ejection time with the polymer length for short polymers. However, for asymptotically long polymers, tw(s) predicts linear scaling.

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  • Received 15 February 2017

DOI:https://doi.org/10.1103/PhysRevE.95.052418

©2017 American Physical Society

Physics Subject Headings (PhySH)

Polymers & Soft MatterStatistical Physics & ThermodynamicsPhysics of Living SystemsFluid Dynamics

Authors & Affiliations

J. Piili, P. M. Suhonen, and R. P. Linna*

  • Department of Computer Science, Aalto University, P. O. Box 15400, FI-00076 Aalto, Finland

  • *Author to whom all correspondence should be addressed: riku.linna@aalto.fi

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Issue

Vol. 95, Iss. 5 — May 2017

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