Simulating water with rigid non-polarizable models: a general perspective

Abstract

Over the last forty years many computer simulations of water have been performed using rigid non-polarizable models. Since these models describe water interactions in an approximate way it is evident that they cannot reproduce all of the properties of water. By now many properties for these kinds of models have been determined and it seems useful to compile some of these results and provide a critical view of the successes and failures. In this paper a test is proposed in which 17 properties of water, from the vapour and liquid to the solid phases, are taken into account to evaluate the performance of a water model. A certain number of points between zero (bad agreement) and ten (good agreement) are given for the predictions of each model and property. We applied the test to five rigid non-polarizable models, TIP3P, TIP5P, TIP4P, SPC/E and TIP4P/2005, obtaining an average score of 2.7, 3.7, 4.7, 5.1, and 7.2 respectively. Thus although no model reproduces all properties, some models perform better than others. It is clear that there are limitations for rigid non-polarizable models. Neglecting polarizability prevents an accurate description of virial coefficients, vapour pressures, critical pressure and dielectric constant. Neglecting nuclear quantum effects prevents an accurate description of the structure, the properties of water below 120 K and the heat capacity. It is likely that for rigid non-polarizable models it may not be possible to increase the score in the test proposed here beyond 7.6. To get closer to experiment, incorporating polarization and nuclear quantum effects is absolutely required even though a substantial increase in computer time should be expected. The test proposed here, being quantitative and selecting properties from all phases of water can be useful in the future to identify progress in the modelling of water.

Hybrid molecular-continuum simulations of water flow through carbon nanotube membranes of realistic thickness

“…This software has been validated over a broad range of applications (Macpherson and Reese 2008;Ritos et al 2013;Dongari et al 2011) including flow of water through carbon nanotubes Ritos et al 2014;. In all our simulations we use the TIP4P/2005 water model (Abascal and Vega 2005;Vega and Abascal 2011) with a Lennard-Jones potential for water-carbon interactions that has the following intermolecular parameters: σ CO = 0.319 nm and ǫ CO = 0.427 kJ mol −1 .…”

Diffusion coefficient and shear viscosity of rigid water models

“…These models vary in the number of considered interaction sites, their flexibility or rigidity and their treatment or neglect of polarizability. Reviews of water models [1][2][3] have addressed their relative merits to model the thermodynamic (e.g. phase diagram or heat capacities), structural and dynamic properties of water.…”

How Short Is Too Short for the Interactions of a Water Potential? Exploring the Parameter Space of a Coarse-Grained Water Model Using Uncertainty Quantification

“…62 The T MD for mW UQ is 23 K below the T m , similar to the mW model and 5% lower than the experimental value of 277 K. The lack of hydrogen atoms in this family of coarse-grained models results in the loss of all rotational contributions to the entropy. This precludes the possibility of simultaneously reproducing T m and ΔH m .…”

“…64 Vega and Abascal provided a comprehensive summary of properties of rigid nonpolarizable atomistic models of water and demonstrated that trade off in the accuracy in certain properties results in dramatic changes in the global representability of the models. 62 Due to the effect of averaging over degrees of freedom, coarse-grained models are not capable of reproducing all properties of interest of the finer resolution model (or the experimental system) simultaneously. Therefore, when a coarse-grained model is parametrized, some properties must be prioritized and it must be ensured that the model derived has adequate fidelity for those properties.…”