Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions

The variational method is applied to the low-energy positron scattering and annihilation problem. The ultimate aim of the investigation is to find a computationally economical way of accounting for strong electron–positron correlations, including the effect of virtual positronium formation. The meth...

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Main Authors: Sarah Gregg, Gleb Gribakin
Format: Article
Language:English
Published: MDPI AG 2022-09-01
Series:Atoms
Subjects:
Online Access:https://www.mdpi.com/2218-2004/10/4/97
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author Sarah Gregg
Gleb Gribakin
author_facet Sarah Gregg
Gleb Gribakin
author_sort Sarah Gregg
collection DOAJ
description The variational method is applied to the low-energy positron scattering and annihilation problem. The ultimate aim of the investigation is to find a computationally economical way of accounting for strong electron–positron correlations, including the effect of virtual positronium formation. The method is applied to the study of elastic <i>s</i>-wave positron scattering from a hydrogen atom. A generalized eigenvalue problem is set up and solved to obtain <i>s</i>-wave positron–hydrogen scattering phase shifts within <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>8</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula> rad of accepted values. This is achieved using a small number of terms in the variational wavefunction; in particular, only nine terms that depend on the electron–positron distance are included. The annihilation parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mi>eff</mi></msub></semantics></math></inline-formula> is also calculated and is found to be in good agreement with benchmark calculations.
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spelling doaj.art-eb4b25ad336e43fea0650b5525c0f81a2023-11-24T13:13:33ZengMDPI AGAtoms2218-20042022-09-011049710.3390/atoms10040097Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable WavefunctionsSarah Gregg0Gleb Gribakin1School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UKSchool of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, UKThe variational method is applied to the low-energy positron scattering and annihilation problem. The ultimate aim of the investigation is to find a computationally economical way of accounting for strong electron–positron correlations, including the effect of virtual positronium formation. The method is applied to the study of elastic <i>s</i>-wave positron scattering from a hydrogen atom. A generalized eigenvalue problem is set up and solved to obtain <i>s</i>-wave positron–hydrogen scattering phase shifts within <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>8</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula> rad of accepted values. This is achieved using a small number of terms in the variational wavefunction; in particular, only nine terms that depend on the electron–positron distance are included. The annihilation parameter <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>Z</mi><mi>eff</mi></msub></semantics></math></inline-formula> is also calculated and is found to be in good agreement with benchmark calculations.https://www.mdpi.com/2218-2004/10/4/97theoretical atomic and molecular physicspositronhydrogenannihilationphase shiftscattering
spellingShingle Sarah Gregg
Gleb Gribakin
Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions
Atoms
theoretical atomic and molecular physics
positron
hydrogen
annihilation
phase shift
scattering
title Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions
title_full Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions
title_fullStr Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions
title_full_unstemmed Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions
title_short Calculation of Low-Energy Positron-Atom Scattering with Square-Integrable Wavefunctions
title_sort calculation of low energy positron atom scattering with square integrable wavefunctions
topic theoretical atomic and molecular physics
positron
hydrogen
annihilation
phase shift
scattering
url https://www.mdpi.com/2218-2004/10/4/97
work_keys_str_mv AT sarahgregg calculationoflowenergypositronatomscatteringwithsquareintegrablewavefunctions
AT glebgribakin calculationoflowenergypositronatomscatteringwithsquareintegrablewavefunctions