Highly coarse-grained polarisable water models for mesoscopic simulations.

Area of Science:

• Soft condensed matter physics
• Computational chemistry
• Materials science

Background:

• Accurate modeling of polar solvents, such as water, is crucial for understanding soft condensed matter properties.
• Representing the dielectric nature, including molecular charge distributions and network structuring, is essential for polar solvents.
• Integrating these dielectric phenomena into larger-than-atomistic simulation techniques like coarse-grained molecular dynamics (CG-MD) and dissipative particle dynamics (DPD) remains a challenge.

Purpose of the Study:

• To develop and justify a suitable coarse-graining level for polar solvents in CG-MD simulations.
• To enable comparison of polar CG models against underlying atomistic models.
• To adapt a non-polar DPD water model for simulations involving liquid electrolytes and solvated organic membranes.

Main Methods:

• Polarization of a previously developed non-polar DPD water model.
• Simulation of liquid electrolytes and solvated organic membranes using the polarized DPD water model.
• Comparison of the polarized DPD water model's dielectric properties against the TIP3P water model.
• Assessment of changes in properties already well-represented by the non-polar model.

Main Results:

• A novel approach to determine the appropriate coarse-graining level for polar solvents in CG-MD simulations.
• Successful polarization of a non-polar DPD water model, making it suitable for dielectric medium simulations.
• Quantitative comparison of the new polar CG model's performance against an atomistic model (TIP3P water).

Conclusions:

• The proposed method provides a viable strategy for coarse-graining polar solvents, capturing essential dielectric properties.
• The polarized DPD water model demonstrates fitness as a dielectric medium for simulating complex systems like electrolytes and membranes.
• This work advances the application of CG-MD and DPD methods in studying soft condensed matter systems with polar components.