Quantum chemical approach for positron annihilation spectra of atoms and molecules beyond plane-wave approximation

Yasuhiro Ikabata, Risa Aiba, Toru Iwanade, Hiroaki Nishizawa, Feng Wang, Hiromi Nakai

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

We report theoretical calculations of positron-electron annihilation spectra of noble gas atoms and small molecules using the nuclear orbital plus molecular orbital method. Instead of a nuclear wavefunction, the positronic wavefunction is obtained as the solution of the coupled Hartree-Fock or Kohn-Sham equation for a positron and the electrons. The molecular field is included in the positronic Fock operator, which allows an appropriate treatment of the positron-molecule repulsion. The present treatment succeeds in reproducing the Doppler shift, i.e., full width at half maximum (FWHM) of experimentally measured annihilation (γ-ray) spectra for molecules with a mean absolute error less than 10%. The numerical results indicate that the interpretation of the FWHM in terms of a specific molecular orbital is not appropriate.

Original languageEnglish
Article number184110
JournalJournal of Chemical Physics
Volume148
Issue number18
DOIs
Publication statusPublished - 2018 May 14

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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