Stokes–Einstein relation without hydrodynamic diameter in the TIP4P/Ice water model

Abstract

It is demonstrated that self-diffusion and shear viscosity data for the TIP4P/Ice water model reported recently [Baran et al., J. Chem. Phys. 158, 064503 (2023)] obey the microscopic version of the Stokes–Einstein relation without the hydrodynamic diameter.

Computing Accurate True Self-Diffusion Coefficients and Shear Viscosities Using the OrthoBoXY Approach

“…91 92 The value of α SE ≈ 0.15 for these conditions has recently been confirmed from experimental data for dense supercritical methane. 93 The value of α SE ≈ 0.15 was also reported from an analysis of simulations of TIP4P/ice water by Khrapak and Khrapak,94 which is in perfect agreement with our results for the TIP4P/2005 model. Considering that s X = (V/N) 1/3 is a rather crude approximation of the molecular diameter for complex molecules and that the influence of the density cannot be discussed here due to the lack of available systematic data, one might, nevertheless, argue that methanol falls on the "stick" side of the spectrum, while dimethyl ether and triglyme are on the "slip" side.…”

“…Note that the two ethers exhibit considerably larger values than the two other components, which are capable of forming hydrogen bonds. This behavior is perhaps even better reflected by the dimensionless “Stokes–Einstein parameter” − α SE = D 0 η s X k B T = 1 6 π · s normalX R hyd given in Table . The hydrodynamic theory for macroscopic spheres gives α SE ≈ 1/( c π) ranging from 0.106 ( c = 3) to 0.159 ( c = 2) for “stick” and “slip” boundary conditions, respectively.…”

Correlations between the Shear Viscosity and Thermal Conductivity Coefficients of Dense Simple Liquids

“…[21] and the applicability of the SE relation has been confirmed. A few recent examples confirming the applicability of SE relation to real liquids include liquid iron at conditions of planetary cores [22], dense supercritical methane (at least for the most state points investigated) [23,24], silicon melt at high temperatures [25], and liquid water modelled by the TIP4P/Ice model [26,27] (which was specifically designed to deal with water near the fluid-solid phase transition and solid-phase properties [28]).…”

System Size Dependence of the Diffusion Coefficients in MD Simulations: A Simple Correction Formula for Pure Dense Fluids

“…Several important nonspherical molecular liquids have been examined using numerical simulations in ref , and the applicability of the SE relation has been confirmed. A few recent examples confirming the applicability of SE relation to real liquids include liquid iron at conditions of planetary cores, dense supercritical methane (at least for the most state points investigated), , silicon melt at high temperatures, and liquid water modeled by the TIP4P/Ice model , (which was specifically designed to deal with water near the fluid–solid phase transition and solid-phase properties).…”