Coarse-grained polarizable soft solvent models, with applications in dissipative particle dynamics.

Area of Science:

• Computational chemistry
• Soft matter physics

Background:

• Dissipative particle dynamics (DPD) models are crucial for simulating soft matter systems.
• Accurate representation of solvent polarization is essential for reliable DPD simulations.

Purpose of the Study:

• To critically evaluate explicitly polarizable soft solvent models for DPD.
• To assess the accuracy of these models in predicting dielectric properties and related phenomena.

Main Methods:

• Linear response theory with the fluctuating box dipole method was used to calculate dielectric permittivity.
• Test cases included ion desorption from an oil-water interface and computation of the Kirkwood factor (gK).
• Dipole-dipole correlation functions were analyzed.

Main Results:

• The Kirkwood factor (gK) consistently ranged from 0.7 to 0.8, indicating non-negligible dipole-dipole correlations.
• Onsager theory over-predicted dielectric permittivity by 20%-30% due to these correlations.
• First-order Wertheim perturbation theory accurately estimated the mean square molecular dipole moment.

Conclusions:

• Explicitly polarizable soft solvent models exhibit significant dipole-dipole correlations.
• Standard theories like Onsager's may overestimate dielectric permittivity in these models.
• Refined theoretical approaches are needed for accurate modeling of polarizable solvents in DPD.