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Nonadiabatic forces in ion-solid interactions: the initial stages of radiation damage
Alfredo A Correa1, Jorge Kohanoff, Emilio Artacho
1Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
Physical Review Letters
|September 26, 2012
Summary
This study reveals that electronic excitations significantly alter interatomic forces during radiation damage, unlike the standard adiabatic approximation. This uncovers new effects in early-stage radiation damage cascades.
Area of Science:
- Materials Science
- Computational Physics
- Quantum Chemistry
Background:
- The Born-Oppenheimer approximation is fundamental for simulating radiation damage.
- Real materials exhibit nonadiabatic energy exchange between electrons and nuclei.
- Understanding these nonadiabatic effects is crucial for accurate simulations.
Purpose of the Study:
- To investigate the impact of electronic excitations on interatomic forces during radiation damage.
- To explore the connection between electronic and nuclear stopping in nonadiabatic processes.
- To uncover novel effects in the early stages of radiation damage cascades.
Main Methods:
- Utilizing time-dependent density functional theory (TD-DFT).
- Calculating electronic excitations induced by energetic protons in Aluminum (Al).
- Analyzing the influence of these excitations on interatomic forces.
Main Results:
- Electronic excitations substantially modify interatomic forces compared to the adiabatic approximation.
- A significant, non-trivial connection between electronic and nuclear stopping is identified.
- These findings highlight deviations from predictions based solely on adiabatic models.
Conclusions:
- Nonadiabatic effects are critical for accurately modeling radiation damage.
- The study reveals new physics in early radiation damage cascade stages.
- This work necessitates a re-evaluation of simulation methods for materials under irradiation.
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