Berlin 2015 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Polymer dynamics
CPP 21.2: Talk
Tuesday, March 17, 2015, 09:45–10:00, C 264
Numerical rate theory approach to polymer escape — •Harri Mökkönen1,2, Tapio Ala-Nissila1, and Hannes Jónsson1,2 — 1Department of Applied Physics and COMP CoE, Aalto University School of Science, P.O. Box 1100, FIN-00076 Aalto, Espoo, Finland — 2Faculty of Physical Sciences, University of Iceland, Reykjavik, Iceland
The polymer escape problem in an external double well potential is studied. The polymer is known to cross the energy barrier in a coiled form below critical length NC and in a stretched form above NC, corresponding to so called "kink" solution in instanton theory [1,2]. We perform Brownian dynamics simulations to obtain the crossing rate RMD as a function of the chain length N and the spring constant K. We numerically find the minimum energy path of the transition and by using the harmonic approximation of transition state theory recover the crossing rate RHTST agreeing with the simulations up to NC. Above NC the energy barrier of the transition becomes flat so the crossing rate by harmonic approximation fails to give the quantitatively correct rate. We study the diffusive mechanism on top of the flat barrier to obtain dynamical corrections f(N) for the harmonic approximation of the crossing rate R′ = f(N) RHTST.
[1] S. K. Lee and W. Sung, Phys. Rev. E 63, 021115 (2001).
[2] H. Mökkönen, T. Ikonen, H. Jonssón, T. Ala-Nissila, J. Chem. Phys. 140, 054907 (2014).