Temperature relaxation in binary hard-sphere mixture system: Molecular dynamics and kinetic theory study.

Area of Science:

• Computational physics
• Statistical mechanics
• Biophysics

Background:

• Temperature relaxation is critical for understanding nanoscale systems, particularly in crowded cellular environments.
• Discrepancies in temperature have been experimentally observed in living cells, necessitating theoretical explanations.

Purpose of the Study:

• To computationally describe temperature relaxation in binary hard-sphere mixture systems.
• To compare molecular dynamics (MD) simulations with renormalized kinetic theory for temperature equilibration.
• To analyze deviations and their causes in nanoscale conditions.

Main Methods:

• Event-driven molecular dynamics (MD) simulations of three binary hard-sphere systems with varying parameters.
• Renormalized kinetic theory using Percus-Yevick approximation for correlation functions.
• Kullback-Leibler divergence to evaluate deviations from equilibrium velocity distributions.

Main Results:

• Both MD simulations and kinetic theory showed fair agreement in describing temperature relaxation.
• Slight deviations were observed in the femto- to picosecond range for systems with significantly different initial component temperatures (e.g., 300 K vs 1000 K).
• Discrepancies were attributed to the kinetic theory's assumption of fast intra-component temperature relaxation, which is violated in MD simulations.

Conclusions:

• The study provides a quantitative basis for understanding temperature inhomogeneities in nanoscale crowding.
• The findings help reconcile computational and theoretical models of thermal processes in complex biological systems.
• This work aids in experimentally addressing observed temperature variations in cellular environments.