Prediction of shear viscosity of glycerin via molecular dynamic study

Abstract

It is a challenge to predict the accurate value of shear viscosity by molecular simulation since equilibrium molecular dynamics (EMD) requires very large samples employed in the calculation of Green-Kubo equation. Note that non-equilibrium molecular dynamics (NEMD) also needs considerably large systems. Particularly for the high viscous materials, there has been little attempt to estimate their viscosities correctly via molecular simulation techniques. In this study, the shear viscosity of glycerin, which is highly viscous, was estimated. Prior to calculations of its shear viscosity, several forcefields were tested with thermodynamic properties of glycerin calculated by running MD simulations. Strikingly, even though thermodynamic properties were well matched with experimental values, the shear viscosities calculated by MD simulations were estimated very low. We conjecture that these relatively low shear viscosities were caused by weakly assigned non-bonding interatomic forces. This claim was suggested by the improved results that the shear viscosity values can be further increased through the correction of the van der Waals energy terms.