Differential cross sections for elastic positron-H2collisions using the R-matrix method
- 28 March 1990
- journal article
- Published by IOP Publishing in Journal of Physics B: Atomic, Molecular and Optical Physics
- Vol. 23 (6) , 1005-1016
- https://doi.org/10.1088/0953-4075/23/6/009
Abstract
Results are presented for positron-H2 collision cross sections for energies below the positronium formation threshold. Calculations are performed with a variety of target representations, including full configuration interaction within a basis of Slater-type orbitals, and several models. The most sophisticated model includes the use of pseudo-excited electronic states of the target to account for intermediate-range polarisation effects. Short- and long-range polarisation effects are also considered. Calculations are performed for Sigma g+, Sigma u+, Pi u, Pi g, Delta g and Delta u symmetries which are combined to give differential cross sections as a function of energy. These calculations underestimate the Sigma g+ eigenphase sum but perform better for the higher symmetries. The differential cross sections show a minimum for angles about 45' which should be amenable to experiment. A computationally more efficient reformulation of the positron-molecule scattering problem is presented within the R-matrix method. Corrections are given for some previously published results.Keywords
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