Positron collisions with molecular hydrogen: cross sections and annihilation parameters calculated using theR-matrix with pseudo-states method

Rui Zhang; K Baluja; Jan Franz; Jonathan Tennyson

doi:10.1088/0953-4075/44/3/035203

Positron collisions with molecular hydrogen: cross sections and annihilation parameters calculated using theR-matrix with pseudo-states method

Abstract

The molecular R-matrix with pseudo-states (MRMPS) method is employed to study positron collisions with H2. The calculations employ pseudo-continuum orbital sets containing up to h (l = 5) functions. Use of these high l functions is found to give converged eigenphase sums. Below the positronium formation threshold, the calculated cross sections agree with other high-accuracy theories and generally with the measurements. Calculation of the positron annihilation parameter Zeff with the MRMPS wavefunctions gives values significantly higher than other R-matrix wavefunctions but still do not completely converge with h functions. Extrapolation to higher l-values leads to a predicted value of Zeff for H2 of about 10.4. The MRMPS method is both completely general and ab initio; it can therefore be applied to positron collisions with other molecular targets.

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Authors (4)

Rui Zhang
- University College London Department of Physics and Astronomy
K Baluja
- University of Delhi Department of Physics and Astrophysics
Jan Franz dr hab.
- University College London Department of Physics and Astronomy
Jonathan Tennyson
- University College London Department of Physics and Astronomy

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DOI:: Digital Object Identifier (open in new tab) 10.1088/0953-4075/44/3/035203
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Category:: Articles
Type:: artykuł w czasopiśmie wyróżnionym w JCR
Published in:: JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS no. 44, edition 3, pages 1 - 9,
ISSN: 0953-4075
Language:: English
Publication year:: 2011
Bibliographic description:: Zhang R., Baluja K., Franz J., Tennyson J.: Positron collisions with molecular hydrogen: cross sections and annihilation parameters calculated using theR-matrix with pseudo-states method// JOURNAL OF PHYSICS B-ATOMIC MOLECULAR AND OPTICAL PHYSICS. -Vol. 44, iss. 3 (2011), s.1-9
DOI:: Digital Object Identifier (open in new tab) 10.1088/0953-4075/44/3/035203
Verified by:: Gdańsk University of Technology