Communication: Fast and local predictors of the violation of the Stokes-Einstein law in polymers and supercooled liquids.

J Chem Phys

Dipartimento di Fisica Enrico Fermi, Università di Pisa, Largo B. Pontecorvo 3, I-56127 Pisa, Italy.

Published: June 2012

The violation of the Stokes-Einstein (SE) law is investigated in a melt of linear chains by extensive molecular-dynamics simulations. It is found that the SE breakdown is signaled (with 5% uncertainty) by the monomer mean-square displacement on the picosecond time scale. On this time scale the displacements of the next-next-nearest neighbors are uncorrelated. It is shown that: (i) the SE breakdown occurs when is smaller than the breadth of the distribution of the square displacements to escape from the first-neighbors cage, (ii) the dynamical heterogeneity affects the form of the master curve of the universal scaling between the structural relaxation and .

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http://dx.doi.org/10.1063/1.4725522DOI Listing

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