First principles nonequilibrium plasma mixing

Area of Science:

• Plasma Physics
• Materials Science
• Computational Chemistry

Background:

• Understanding material interpenetration is crucial for inertial confinement fusion (ICF) targets.
• Warm, dense matter (WDM) presents unique challenges due to combined quantum and classical effects.

Purpose of the Study:

• To investigate the interpenetration dynamics of deuterium-tritium (DT) and carbon (C) in WDM.
• To compare classical and quantum mechanical simulation results for diffusion processes.

Main Methods:

• Nonequilibrium classical molecular dynamics (MD) with Yukawa potential.
• Quantum-mechanical MD using orbital-free density functional theory (OF-DFT).
• Simulations covered densities of 2.5-5.5 g/cm³ and temperatures of 10-100 eV.

Main Results:

• At times > 1 ps, component concentrations follow Fick's law for a classical fluid.
• Diffusion is governed by the mutual diffusion coefficient of the mixed system.
• At times < 1 ps, non-Fickian dynamics are observed, influenced by electron probability density.

Conclusions:

• Classical and quantum simulations provide insights into WDM diffusion.
• Fick's law is applicable at longer timescales, but microscopic effects dominate early dynamics.
• Accurate modeling of electron density is essential for understanding early-stage interpenetration.