Sound speed in Yukawa one-component plasmas across coupling regimes

Area of Science:

• Plasma Physics
• Condensed Matter Physics

Background:

• Yukawa one-component plasma (YOCP) models charged particles with screened Coulomb interactions.
• YOCP systems are characterized by screening parameter (κ) and coupling strength (Γ).
• A longitudinal acoustic mode governs the collective spectrum in both weak and strong coupling regimes.

Purpose of the Study:

• Investigate the sound speed evolution in YOCP from weak to strong coupling.
• Identify distinct physical domains within the (κ, Γ) parameter space.
• Compare simulation data with theoretical models for YOCP behavior.

Main Methods:

• Utilized molecular dynamics (MD) simulations to analyze the dynamic structure function S(k,ω).
• Obtained high-quality data for Γ ranging from 0.1 to 10000 and κ from 0.5 to 5.
• Focused on the low-frequency domain and long-wavelength limit to determine sound speed.

Main Results:

• Identified five domains in the (κ, Γ) parameter space with distinct physical behaviors.
• Characterized transitions between collective, collision-dominated, individual particle, and quasilocalized behaviors.
• Found that sound speed depends on the ratio of wave phase velocity to thermal speed (w).

Conclusions:

• The study provides a comprehensive map of YOCP behavior across different coupling and screening regimes.
• MD simulations offer a robust method for studying complex plasma systems.
• Understanding these domains is crucial for accurately modeling various physical systems described by YOCP.