Eur. Phys. J. E 10, 369-385 (2003)
DOI: 10.1140/epje/i2002-10122-1

Dynamical properties of the slithering-snake algorithm: A numerical test of the activated-reptation hypothesis

L. Mattioni¹, J.P. Wittmer¹, J. Baschnagel², J.-L. Barrat¹ and E. Luijten<sup>3, 4

1</sup>  Département de Physique des Matériaux, Université Claude Bernard and CNRS, 69622 Villeurbanne Cedex, France
²  Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg, France
³  Institut für Physik, Johannes-Gutenberg-Universität Mainz, 55099 Mainz, Germany
⁴  Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL 61801, USA

jwittmer@dpm.univ-lyon1.fr

(Received 18 December 2002 and Received in final form 22 March 2003 / Published online: 12 May 2003)

Abstract
Correlations in the motion of reptating polymers in a melt are investigated by means of Monte Carlo simulations of the three-dimensional slithering-snake version of the bond-fluctuation model. Surprisingly, the slithering-snake dynamics becomes inconsistent with classical reptation predictions at high chain overlap (created either by chain length N or by the volume fraction of occupied lattice sites), where the relaxation times increase much faster than expected. This is due to the anomalous curvilinear diffusion in a finite time window whose upper bound is set by the density of chain ends . Density fluctuations created by passing chain ends allow a reference polymer to break out of the local cage of immobile obstacles created by neighboring chains. The dynamics of dense solutions of "snakes" at is identical to that of a benchmark system where all chains but one are frozen. We demonstrate that the subdiffusive dynamical regime is caused by the slow creeping of a chain out of its correlation hole. Our results are in good qualitative agreement with the activated-reptation scheme proposed recently by Semenov and Rubinstein (Eur. Phys. J. B, 1 (1998) 87). Additionally, we briefly comment on the relevance of local relaxation pathways within a slithering-snake scheme. Our preliminary results suggest that a judicious choice of the ratio of local to slithering-snake moves is crucial to equilibrate a melt of long chains efficiently.

PACS
61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling.
83.10.Kn - Reptation and tube theories.
83.80.Sg - Polymer melts.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003