Static Dielectric Constant from Simulations Revisited: Fluctuations or External Field?

Area of Science:

• Computational chemistry and physics
• Materials science

Background:

• Determining static relative permittivity (dielectric constant) is crucial for understanding material properties.
• Molecular simulations offer a powerful tool for calculating these properties under various conditions.

Purpose of the Study:

• To compare the efficiency and accuracy of two methods for calculating static relative permittivity in molecular simulations.
• To investigate the role of saturation and boundary conditions in these calculations.
• To develop and apply an improved method for polarizable water models.

Main Methods:

• Comparison of the fluctuation formula and external electric field methods for static relative permittivity calculation.
• Analysis of systematic and statistical errors using dimensionless saturation.
• Development of an extrapolation scheme for the external electric field method.
• Application to nonpolarizable (SPC/E, TIP4P/2005, NE6) and polarizable (POL3, DC97, BK3) water models.

Main Results:

• Both fluctuation and external field methods demonstrate equivalent computational efficiency.
• Saturation effects were analyzed for both methods, revealing dependencies on particle number, medium permittivity, and field intensity.
• An extrapolation scheme was successfully applied to various water models, particularly beneficial for polarizable ones.

Conclusions:

• The fluctuation and external field methods are equally efficient for calculating static relative permittivity.
• The proposed extrapolation scheme enhances the accuracy of the external field method, especially for polarizable systems.
• Understanding saturation is key to optimizing permittivity calculations in molecular simulations.