Many-body theory of positron-molecule interactions
ORAL · Invited
Abstract
Positrons are unique probes of matter with important applications in materials science, astrophysics and medical imaging. Low-energy positron interactions with atoms and molecules are characterized by strong correlations, e.g., polarization of the molecular electron cloud, screening of the electron-positron Coulomb interaction, and virtual-Ps formation [1]. They substantially modify scattering, enhance annihilation rates by orders of magnitudes, and can enable positron binding. They also make the theoretical description of the positron-molecule system a challenging many-body problem.
I will review our many-body theory of positron-molecule interactions and its computational implementation in our EXCITON+ code [1,2]. I will present recent calculations of positron binding energies for polyatomic molecules that gave unprecedented agreement with experiment and provided fundamental insight, e.g., quantifying the roles of distinct correlations and molecular orbitals [1], identifying and explaining trends within molecular families including the effect of halogenation in hydrocarbons [3], and the competing role of dipoles and pi bonds in heterocyclics [4]. I will also discuss its extension to positron scattering [5], and to positronic-bonded molecules [6] (in which two dianions that would otherwise repel are bonded by a positron).
Beyond providing fundamental understanding required to support ongoing experiments and advance antimatter technologies (traps, accumulators, beams and PET), our results provides benchmarks for other methods tackling the computational many-body problem.
[1] J. Hofierka ,..., DGG, Nature 606, 688 (2022).
[2] C. H. Patterson, Phys. Rev. Mater. 3, 043804 (2019).
[3] J. Cassidy, ..., DGG, Phys. Rev. A 109, L040801 (2024).
[4] E. Arthur-Baidoo, ... , DGG, arXiv:2312.02779, Phys. Rev. A (in press).
[5] C. M. Rawlins, ..., DGG, Phys. Rev. Lett. 130, 263001 (2023).
[6] J. Cassidy,..., DGG, J. Chem. Phys. 160, 084304, Emerg. Inv. Spec. Collec. (2024).
I will review our many-body theory of positron-molecule interactions and its computational implementation in our EXCITON+ code [1,2]. I will present recent calculations of positron binding energies for polyatomic molecules that gave unprecedented agreement with experiment and provided fundamental insight, e.g., quantifying the roles of distinct correlations and molecular orbitals [1], identifying and explaining trends within molecular families including the effect of halogenation in hydrocarbons [3], and the competing role of dipoles and pi bonds in heterocyclics [4]. I will also discuss its extension to positron scattering [5], and to positronic-bonded molecules [6] (in which two dianions that would otherwise repel are bonded by a positron).
Beyond providing fundamental understanding required to support ongoing experiments and advance antimatter technologies (traps, accumulators, beams and PET), our results provides benchmarks for other methods tackling the computational many-body problem.
[1] J. Hofierka ,..., DGG, Nature 606, 688 (2022).
[2] C. H. Patterson, Phys. Rev. Mater. 3, 043804 (2019).
[3] J. Cassidy, ..., DGG, Phys. Rev. A 109, L040801 (2024).
[4] E. Arthur-Baidoo, ... , DGG, arXiv:2312.02779, Phys. Rev. A (in press).
[5] C. M. Rawlins, ..., DGG, Phys. Rev. Lett. 130, 263001 (2023).
[6] J. Cassidy,..., DGG, J. Chem. Phys. 160, 084304, Emerg. Inv. Spec. Collec. (2024).
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Presenters
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Dermot G Green
Queen's University Belfast
Authors
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Dermot G Green
Queen's University Belfast