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Dirac bubble potential for He-He and inadequacies in the continuum: Comparing an analytic model with elastic
1LUNAM Université, Université d'Angers, CNRS UMR 6200, Laboratoire MOLTECH-Anjou, 2 Bd Lavoisier, 49045 Angers, France.
The Journal of Chemical Physics
|January 16, 2017
Summary
We improved the Dirac bubble potential model for helium-helium interactions by adding a potential wall. This revised model accurately describes elastic collision cross sections and cold collision experiments, enhancing predictive power.
Area of Science:
- Atomic and Molecular Physics
- Quantum Chemistry
- Scattering Theory
Background:
- The Dirac bubble potential model inadequately describes helium-helium (He-He) interactions, failing to account for short-range repulsion.
- This inadequacy limits its ability to quantitatively reproduce experimental glory scattering data for He-He systems.
- Previous applications showed success with helium dimers and trimers but failed with continuum interactions.
Purpose of the Study:
- To address the limitations of the Dirac bubble potential model for He-He interactions.
- To develop an improved model that accurately describes He-He elastic collision cross sections.
- To provide a model with enhanced predictive power and didactic value.
Main Methods:
- Supplementing the Dirac bubble potential with an energy-dependent potential wall of calculated thickness.
- Testing the revised model against variable-energy elastic collision cross section data for He-He isotopes.
- Comparing model predictions with cold collision experiments in the low-energy regime.
Main Results:
- The extended Dirac bubble potential model achieves agreement with experimental elastic collision cross sections for 4He-4He, 3He-4He, and 3He-3He.
- Consistency is observed between the revised model and cold collision experiments at very low energies.
- The extended model reduces to the original Dirac bubble potential in the low-energy limit.
Conclusions:
- The addition of a potential wall resolves the inadequacy of the Dirac bubble potential for He-He interactions.
- The revised, analytic model offers improved accuracy and predictive capabilities for atomic helium collisions.
- The model holds significant didactic value for understanding interatomic potentials and scattering phenomena.
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