System Size Dependence of the Diffusion Coefficients in MD Simulations: A Simple Correction Formula for Pure Dense...

Area of Science:

• Computational physics
• Chemical physics
• Materials science

Background:

• Molecular dynamics (MD) simulations are crucial for understanding liquid properties.
• Simulations often use periodic boundary conditions, introducing finite-size effects.
• Accurate self-diffusion coefficients are essential for transport phenomena studies.

Purpose of the Study:

• To develop a practical correction formula for self-diffusion coefficients.
• To relate simulation results to the thermodynamic limit.
• To provide a method for improving the accuracy of MD simulations for dense liquids.

Main Methods:

• Derivation of a correction formula: D = D0(1 - γN^-1/3).
• Application of the formula to pure dense fluids.
• Validation using molecular dynamics simulations with varying system sizes and geometries.

Main Results:

• A simple, practical formula was established to correct finite-size effects.
• The correction factor γ depends on simulation cell geometry.
• γ ≃ 1.0 for the common cubic simulation cell geometry.
• The formula's validity was confirmed by recent MD simulation results.

Conclusions:

• The proposed formula accurately corrects self-diffusion coefficients in MD simulations.
• This correction bridges the gap between simulation data and the thermodynamic limit.
• The findings enhance the reliability of MD simulations for dense fluid transport properties.