Ab Initio Prediction of a Negative Barkas Coefficient for Slow Protons and Antiprotons in LiF
- Creators
- Qi, Xixi
- Bruneval, Fabien
- Maliyov, Ivan
Abstract
We report the ab initio prediction of a negative Barkas coefficient in lithium fluoride (LiF) insulator at low velocity (v < 0.25 a. u., E_(kin) ∼ 2 keV). The electronic stopping power of protons in LiF has been extensively studied both experimentally and theoretically because of a controversial threshold effect. While our time-dependent density-functional theory simulations confirm the presence of a velocity threshold below which the proton stopping power vanishes, our calculations demonstrate that the antiprotons do not experience such a threshold. The combination of those two contrasting behaviors gives rise to an unprecedented negative Barkas effect: the stopping power of antiprotons is larger than that of protons. We identify that the slow antiproton at close encounter destabilizes a p orbital of the F⁻ anion pointing toward the antiproton. This particular orbital becomes highly polarizable and hence contributes much to the stopping power.
Additional Information
© 2022 American Physical Society. (Received 23 September 2021; accepted 5 January 2022; published 24 January 2022) This work was performed using HPC resources from GENCI-TGCC (Grant No. 2021-096018). We are indebted to I. Nagy for having pointed us to the LiF electronic stopping power.Attached Files
Published - PhysRevLett.128.043401.pdf
Supplemental Material - LiF_SupplementalMaterial.pdf
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Additional details
- Eprint ID
- 113102
- Resolver ID
- CaltechAUTHORS:20220125-195124000
- 2021-096018
- Grand Équipement National De Calcul Intensif
- Created
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2022-01-25Created from EPrint's datestamp field
- Updated
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2022-01-25Created from EPrint's last_modified field