Correlation-polarization effects in electron/positron scattering from acetylene: A comparison of computational models

J. Franz, F. A. Gianturco, K. L. Baluja, J. Tennyson, R. Carey, R. Montuoro, R. R. Lucchese, T. Stoecklin, P. Nicholas, T. L. Gibson

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Different computational methods are employed to evaluate elastic (rotationally summed) integral and differential cross sections for low energy (below about 10 eV) positron scattering off gas-phase C2H2 molecules. The computations are carried out at the static and static-plus-polarization levels for describing the interaction forces and the correlation-polarization contributions are found to be an essential component for the correct description of low-energy cross section behavior. The local model potentials derived from density functional theory (DFT) and from the distributed positron model (DPM) are found to produce very high-quality agreement with existing measurements. On the other hand, the less satisfactory agreement between the R-matrix (RM) results and measured data shows the effects of the slow convergence rate of configuration-interaction (CI) expansion methods with respect to the size of the CI-expansion. To contrast the positron scattering findings, results for electron-C2H2 integral and differential cross sections, calculated with both a DFT model potential and the R-matrix method, are compared and analysed around the shape resonance energy region and found to produce better internal agreement.

Original languageEnglish
Pages (from-to)425-434
Number of pages10
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume266
Issue number3
DOIs
StatePublished - Feb 2008

Keywords

  • 31.25.v
  • 34.80.Bm
  • 34.85.+x
  • Computed angular distributions for e/e scattering
  • Electron-molecule scattering
  • Molecular gases
  • Positron-molecule scattering
  • Quantum calculations

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