Electronic stopping power in LiF from first principles.

Area of Science:

• Condensed matter physics
• Materials science
• Computational physics

Background:

• Understanding energy transfer from charged particles to materials is crucial for various applications, including radiation detection and materials modification.
• Electronic stopping power is a key parameter describing energy loss in materials.
• Previous studies have explored stopping power, but detailed comparisons between proton and antiproton interactions in insulators are limited.

Purpose of the Study:

• To calculate the electronic stopping power for protons and antiprotons in Lithium Fluoride (LiF) using first-principles methods.
• To investigate the velocity dependence of energy transfer and identify any threshold velocities.
• To determine the proton/antiproton stopping-power ratio and compare it with experimental findings.

Main Methods:

• Utilizing time-dependent density-functional theory (TD-DFT) for accurate electronic structure calculations.
• Performing first-principles simulations to model the interaction of moving protons and antiprotons with LiF electrons.
• Analyzing the projectile velocity dependence of the calculated electronic stopping power.

Main Results:

• An effective threshold velocity of approximately 0.2 atomic units (a.u.) was identified for both proton and antiproton energy transfer.
• The calculated proton/antiproton stopping-power ratio was found to be approximately 2.4 at velocities slightly above the threshold (v ≈ 0.4 a.u.).
• The energy loss mechanism was observed to be highly localized.

Conclusions:

• The theoretical calculations align well with recent experimental observations for proton and antiproton stopping power in LiF.
• The study confirms the existence of a threshold velocity for significant energy transfer.
• The localized nature of projectile energy loss provides insights into the fundamental interaction mechanisms at the electronic level.