Comparative molecular dynamics simulations of charged solid-liquid interfaces with different water models

Area of Science:

• Computational chemistry
• Physical chemistry
• Materials science

Background:

• Aqueous solid-liquid interfaces (SLIs) are critical in natural and technological processes.
• Molecular dynamics (MD) simulations provide atomistic insights into interfacial phenomena.
• Numerous water models exist, each with specific optimizations, leading to simulation variability.

Purpose of the Study:

• To compare the performance of various water models in simulating charged silica-aqueous solution interfaces.
• To assess the consistency between MD simulations and continuum predictions (Poisson-Boltzmann model).
• To determine the applicability of analytical models for nanoscale SLIs.

Main Methods:

• Comparison of bulk dielectric constants for 11 water models (SPC/Fw, SPC/e, TIPS3p, H2O/DC, TIP3P-Fw, OPC3, TIP3P, TIP3P-FB, TIP3P-ST, FBA/e, TIPS3p-PPPM) with varying NaCl concentrations.
• MD simulations of silica-water interfaces using selected water models.
• Comparison of MD free energy minima with Poisson-Boltzmann model predictions.

Main Results:

• Significant variations in dielectric constants were observed among different water models.
• MD simulations showed consistency with continuum predictions when Stern layer charge and dielectric constant were incorporated.
• Analytical model applicability extends to the nanoscale, contingent on prior knowledge of Stern layer charge.
• Reproducibility issues and analytical method limitations arise at NaCl concentrations above 0.21 M due to ion pairing.

Conclusions:

• The choice of water model significantly impacts MD simulations of charged SLIs.
• Continuum models can be reconciled with MD results for SLIs, especially at the nanoscale.
• The study provides guidance for selecting appropriate water models for interfacial simulations.
• Findings are crucial for advancing MD simulations of electrified and charged interfaces.