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Type: Artigo de periódico
Title: Near-threshold vibrational excitation of H-2 by positron impact: A projection-operator approach
Author: Varella, MTD
Lima, MAP
Abstract: We report vibrational excitation (nu(i)=0 ->nu(f)=1) and total cross sections for positron scattering by H-2. The Feshbach projection operator formalism was employed to vibrationally resolve the fixed-nuclei phase shifts obtained with the Schwinger multichannel method. The near-threshold behavior of the vibrational excitation cross section is in good agreement with available experimental data [Sullivan , Phys. Rev. Lett. 86, 1494 (2001)]. Though our fixed-nuclei calculations do not indicate the existence of a e(+)-H-2 virtual state, a proper description of the T matrix threshold behavior is essential (the adiabatic approximation is inadequate). The projection operator approach has long been a powerful tool for studies of nuclear dynamics in electron-molecule collisions, and its application to positron scattering is timely since couplings to nuclear degrees of freedom are known to be very important at low impact energies.
Country: EUA
Editor: Amer Physical Soc
Citation: Physical Review A. Amer Physical Soc, v. 76, n. 5, 2007.
Rights: aberto
Identifier DOI: 10.1103/PhysRevA.76.052701
Date Issue: 2007
Appears in Collections:Unicamp - Artigos e Outros Documentos

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