Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Poster: Colloids and Complex Liquids

CPP 20.36: Poster

Dienstag, 12. März 2013, 18:15–20:15, Poster C

Determining the shear viscosity of a solvent in the presence of electric fields — •Zoran Miličević¹, David M. Smith², and Ana-Sunčana Smith¹ — ¹Institut für Theoretische Physik and Cluster of Excellence: Engineering of Advanced Materials, Universität Erlangen-Nürnberg, Erlangen, Germany — ²Computer Chemie Centrum, Universität Erlangen-Nürnberg, Erlangen, Germany

The shear viscosity is a very important kinetic property characterizing the macroscopic properties of molecular systems and is hence useful for the parametrization of reliable force fields. However, calculating the shear and bulk viscosities from molecular dynamics simulations is still a challenging task.

Here we study the shear viscosity of water by performing extensive MD simulations using the GROMACS software package and SPC/E model of water (rigid and flexible) as a function of the electric field strength. The latter breaks the otherwise isotropic nature of the solvent. The shear viscosity is related to the autocorrelation function of the off-diagonal elements of the pressure tensor by the Green-Kubo relation, which is used to analyze pure water simulations. Alternatively, the viscosity is calculated from the mobility of a spherical particle, the latter arising from the diffusion constant evaluated in independent simulations. Apart from the fact that different treatments show excellent agreement, we find that the field decreases the component of the shear viscosity perpendicular to the field and increases the components parallel to the field.