Shear viscosity calculations through a reverse nonequilibrium method

In this work we present the result of an algorithm implementation for reverse nonequilibrium molecular dynamics simulation which allows the prediction of viscosity. A non physical momentum flux is imposed by dividing the simulation box into slabs and applying an exchange of the largest negative and positive velocities atoms between the first and central slabs respectively, as result a velocity gradient is produced. This technique has been successfully implemented for atomistic simulations using a molecular dynamics package YASP which works on analytical potential. However, our work focuses on the implementation of RNEMD method into a molecular dynamics code GMQ which works on numerical potential. The developed code provides a reliable tool to predict viscosities for coarse-grained models via RNEMD technique. The results for Lennard-Jones liquids are presented as well as their comparison for both molecular dynamics codes. Our results are also in good agreement with experimental data. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.