Many-body theory of positron-atom interactions

Abstract

A many-body theory approach is developed for the problem of positron-atom scattering and annihilation. Strong electron-positron correlations are included non-perturbatively through the calculation of the electron-positron vertex function. It corresponds to the sum of an infinite series of ladder diagrams, and describes the physical effect of virtual positronium formation. The vertex function is used to calculate the positron-atom correlation potential and nonlocal corrections to the electron-positron annihilation vertex. Numerically, we make use of B-spline basis sets, which ensures rapid convergence of the sums over intermediate states. We have also devised an extrapolation procedure that allows one to achieve convergence with respect to the number of intermediate-state orbital angular momenta included in the calculations. As a test, the present formalism is applied to positron scattering and annihilation on hydrogen, where it is exact. Our results agree with those of accurate variational calculations. We also examine in detail the properties of the large correlation corrections to the annihilation vertex.

25 pages, 16 figures

References in corpus (4)

• Positronic lithium, an electronically stable Li-e${}^{+}$ ground state
• Mechanisms of positron annihilation on molecules
• Calculation of the positron bound state with the copper atom
• Calculation of positron binding to silver and gold atoms

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• Convergence of CI single center calculations of positron-atom interactions
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• Calculations of positronium-atom scattering using a spherical cavity
• Multichannel Formalism for Positron-Hydrogen Scattering and Annihilation
• Effective radius of ground- and excited-state positronium in collisions with hard walls
• Many-body theory calculations of positronic-bonded molecular dianions
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• A Self-Consistent Model for Positronium Formation from Helium Atoms
• Many-body theory for positronium scattering and pickoff annihilation in noble-gas atoms
• Two-photon Annihilation of Positrons with K-shell Electrons of H-like ions
• Ab initio QED treatment of the two-photon annihilation of positrons with bound electrons
• Coupled cluster theory for positron binding in anions and polyatomic molecules
• Many-body theory predictions of positron binding energies in five-membered heterocycles involving N, O, S and NH substituents