A coarse-grained water model for mesoscale simulation of clay-water interaction

Abstract

Coarse-grained molecular dynamic (CGMD) simulations are the most popular technique in mesoscale modeling. In the fields of applied clay science, significant progresses have been made in coarse-graining clay particles. Meanwhile, various kinds of coarse-grained water models have been developed in the fields of environmental science, chemical physics and biological science to advance the basic understanding of chemical and biological reaction processes in the presence of water. The coarse-grained clay model (Gay-Berne clay model) that has the highest coarsening degree and the most reasonable coarsening theory, however, requires a unique potential function, which is found not compatible with previous coarse-grained water models. In order to simulate mesoscale clay-water interactions using Gay-Berne clay model, a completely new coarse-grained water model was proposed in this study. Five water molecules were embedded into one pseudo spherical water particle. The model parametrization was determined by thermodynamic perturbation method and was verified by comparing the nine physical, mechanical and thermodynamic properties with previous published studies in experiments, full-atomistic water models and other coarse-grained water models. Comparison analysis showed that the properties of water were well reproduced by the newly developed simple coarse-grained water model. In addition, the new coarse-grained water model showed a speed-up factor of 520 in reference with full-atomistic water model. Therefore, the new coarse-grained water model is suitable for coarse-grained simulations and could bridge the gap toward probing the clay-water interaction mechanisms from nano to mesoscale.