Computing dielectric spectra in molecular dynamics simulations: Using a cavity to disentangle self and cross...

Area of Science:

• Computational chemistry
• Materials science
• Statistical mechanics

Background:

• Dielectric spectra are crucial for understanding material properties.
• Standard molecular dynamics (MD) simulations calculate dielectric spectra from total dipole moment fluctuations.
• Long-range electrostatic correlations in MD can be sensitive to boundary conditions.

Purpose of the Study:

• To introduce and evaluate a novel virtual cavity protocol for dielectric spectra calculation in MD simulations.
• To compare the virtual cavity method with the standard dipole moment fluctuation method.
• To assess the sensitivity of the virtual cavity method to noise and boundary conditions.

Main Methods:

• Molecular dynamics (MD) simulations were performed on three non-polarizable systems.
• A virtual cavity protocol was developed, focusing on short-range dipolar correlations.
• The virtual cavity method was compared against the standard method analyzing total dipole moment fluctuations.

Main Results:

• The virtual cavity protocol yields dielectric spectra comparable to the standard method.
• The cavity protocol demonstrates reduced sensitivity to noise.
• The decomposition of dielectric spectra into self and cross contributions was analyzed for both methods.

Conclusions:

• The virtual cavity protocol provides a robust alternative for calculating dielectric spectra in MD simulations.
• This method is less susceptible to noise, enhancing reliability.
• For liquids with high dielectric permittivity, the cavity protocol's self-spectrum aligns with experimental electrostatic boundary conditions.