Parametrizing hydrogen bond interactions in dissipative particle dynamics simulations: The case of water, methanol and their binary mixtures

Abstract

Simulating water has always been a challenge. Due to the intrinsic hydrogen bond interactions, water exhibits structural properties, such as a tetrahedral coordination resulting in a specific Radial Distribution Function (RDF), which are not trivial to predict computationally. In this paper, we attempt to use coarse-grained Dissipative Particle Dynamics (DPD) simulations to parameterize the hydrogen bond interactions without violating the classical DPD framework. We model the hydrogen bond interactions by incorporating a Morse potential, where the parameters are computed by taking the experimental enthalpy of evaporation and hydrogen bond distances as reference. We show that with the proposed procedure the RDF, the coordination number, the isothermal compressibility, and the three-body angular distributions (to demonstrate the tetrahedral structure) of pure water are predicted in great extent compatible with the experiments. To test the applicability of the procedure to mixtures, we simulated pure methanol and methanol/water mixtures at different molar fractions. The predicted RDF profiles for methanol-methanol, methanol-water and water-water represent the characteristic experimental RDF behavior. Moreover, the calculated negative excess volumes as a function of mole fraction compare quite well with the experimentally observed excess volumes. Our findings motivate the further development and use of DPD simulations in modeling hydrogen bond interactions, which are crucial not only in water (or alcohols), but in more complex systems such as biomolecules, proteins or biopolymers.