Finite-size dependence of the bridge function extracted from molecular dynamics simulations

Area of Science:

• Physical Chemistry
• Computational Materials Science
• Statistical Mechanics

Background:

• The bridge function is crucial for understanding liquid systems.
• Molecular dynamics (MD) simulations are widely used but can suffer from finite-size effects.
• Accurate calculation of the static structure factor is essential for materials characterization.

Purpose of the Study:

• To calculate the bridge function for liquid sodium at 373 K.
• To investigate the impact of finite system size on the bridge function and static structure factor.
• To develop a method for correcting finite-size effects in theoretical calculations.

Main Methods:

• Utilized the mean spherical approximation (MSA) to extrapolate the pair distribution function (PDF) from MD simulations.
• Employed two different MD system sizes to assess finite-size dependency.
• Developed and applied a self-consistent procedure to correct for finite-size effects.

Main Results:

• The bridge function strongly depends on the number of particles in the simulation cell.
• Finite-size effects lead to spurious maxima in the static structure factor calculated via the reference hypernetted-chain approximation (RHNC-MD).
• The proposed self-consistent procedure effectively corrects these unphysical manifestations.

Conclusions:

• Finite-size effects are a significant concern in MD simulations of liquid sodium.
• The developed self-consistent method provides an efficient way to obtain accurate static structure factors.
• This work offers a pathway to reliable theoretical predictions for liquid metal properties.