Diffusion coefficient and shear viscosity of rigid water models

TL;DR

This study evaluates the diffusion coefficient and shear viscosity of popular rigid water models, comparing simulation results with experimental data and analyzing the effects of system size on these properties.

Contribution

It provides size-independent estimates of diffusion and viscosity for three water models, highlighting the accuracy of TIP4P/2005 compared to SPC/E and Dang-Chang.

Findings

TIP4P/2005 closely matches experimental data

SPC/E and Dang-Chang overestimate diffusion

All models' viscosities agree well with Green-Kubo results

Abstract

We report the diffusion coefficient and viscosity of popular rigid water models: Two non polarizable ones (SPC/E with 3 sites, and TIP4P/2005 with 4 sites) and a polarizable one (Dang-Chang, 4 sites). We exploit the dependence of the diffusion coefficient on the system size [Yeh and Hummer, J. Phys. Chem. B 108, 15873 (2004)] to obtain the size-independent value. This also provides an estimate of the viscosity of all water models, which we compare to the Green-Kubo result. In all cases, a good agreement is found. The TIP4P/2005 model is in better agreement with the experimental data for both diffusion and viscosity. The SPC/E and Dang-Chang water overestimate the diffusion coefficient and underestimate the viscosity.