Long-range correlations under temperature gradients: A molecular dynamics study of simple fluids

Area of Science:

• Physics
• Soft Matter Physics
• Computational Physics

Background:

• Long-range correlations (LRCs) in fluids under temperature gradients cause enhanced density fluctuations.
• This phenomenon is theoretically and experimentally studied, marked by a q^{-4} divergence in the static structure factor.
• LRCs have not been explored in Hamiltonian particle systems via molecular dynamics (MD) simulations.

Purpose of the Study:

• To report the first molecular dynamics (MD) simulation study observing long-range correlations (LRCs) in Hamiltonian particle systems.
• To demonstrate the presence of LRCs using multiple analytical approaches within MD simulations.
• To validate MD simulations as a tool for studying LRCs.

Main Methods:

• Measuring the static structure factor to observe the characteristic q^{-4} divergence.
• Analyzing the dynamic structure factor for the q^{-4} divergence.
• Comparing MD simulation results with predictions from fluctuating hydrodynamics theory.

Main Results:

• Unambiguous observation of long-range correlations (LRCs) in Hamiltonian particle systems using MD simulations.
• Direct detection of the q^{-4} divergence in both static and dynamic structure factors.
• Quantitative agreement between MD results and fluctuating hydrodynamics predictions.

Conclusions:

• Molecular dynamics (MD) simulations provide a powerful method for studying long-range correlations (LRCs).
• This study establishes MD simulations as a viable complementary tool to theoretical and experimental approaches for LRCs.
• The findings confirm the applicability of fluctuating hydrodynamics in describing LRCs within MD simulations.