Water-Graphene non-bonded interaction parameters: Development and influence on molecular dynamics simulations

Abstract

Molecular dynamics simulations have been extensively used to study water-graphene systems, and the force field parameters are vital for the accuracy of simulation results. Herein, water-graphene non-bonded Lennard-Jones (LJ) parameters were developed according to the experimental water contact angle (θ), and were further validated by the quantum-chemistry calculated water-graphene interaction energy (Eint). The LJ parameters were developed based on various water models, and were employed to simulated a large diversity of water-graphene systems (e.g. water nanodroplet (or one water molecule) on graphene, water slab-graphene interface, graphene nanochannel connected to a water reservoir, water confined in graphene nanochannel, etc.), with thorough comparison against LJ parameters derived from Lorentz-Berthelot mixing rule. All these abundant data were studied in-depth to yield plenty of insights (some were rarely reported) that could be extended to other two-dimensional materials or systems, e.g. linear correlation of cos θ ∼ LJ parameter and the slope is also linear with the reciprocal of water’s surface tension, linear correlation of Eint ∼ density of the 1st water layer on graphene, correlation of Eint ∼ water molecules’ residue time on graphene, (roughly) linear correlation of water density inside graphene 2D nanochannel ∼ water’s diffusivity etc.