Development of non-bonded interaction parameters between hexagonal boron-nitride and water

Abstract

Non-bonded force-field (FF) parameters between a two-dimensional hexagonal boron nitride (hBN) sheet and water molecules were developed. The hBN sheet was modelled using Tersoff potential. Three commonly used water models, namely SPC, SPC/E, and SPC/Fw were utilized to represent water. Particle swarm optimization (PSO) was employed to accelerate the development of accurate FF parameters to reproduce the experimental macroscopic contact angle of a water droplet (∼47°) on the hBN sheet. To the best of our knowledge, this study presents the first example of optimizing hBN-water interactions through reproduction of the macroscopic contact angle of water. A systematic two-step approach was utilized to develop these parameters by using a nanoscopic water droplet with 2000 molecules. In the first step, the hBN-water interactions were optimized to reproduce a macroscopic contact angle of water, ∼47° for a nanoscopic droplet with 2000 molecules (FF Set-I). In the second step, the FF parameters were optimized such that the ∼47° angle was reproduced for the macroscopic water droplet (FF Set-II). The binding energies of an adsorbed water molecule in its prefered configuration on the hBN sheet were approximately −7.49 and −8.08 kJ/mol for Set-I and Set-II, respectively. These values were in good agreement with results from previous studies. Structural and dynamical properties of a water droplet such as the Z-density profile of oxygen atoms, angle made by OH-vector with Z-axis, and the average hydrogen bonds per molecule were also determined to validate the developed FF parameters. All three water models could predict these properties of water at the hBN-water interface with reasonable accuracy.