EPJ D Topical review - Electron-scattering on molecular hydrogen: convergent close-coupling approach

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Published on 24 March 2020

Molecular hydrogen is the simplest neutral molecule, the most abundant molecule in the universe and an important constituent of plasmas with applications in astrophysics, fusion, atmospheric physics, and various industries. Elemental collision processes play an important role in modelling these plasmas, and collisions with electrons have attracted significant interest from both experiment and theory. A number of compilations of cross sections for electron collisions with molecular hydrogen have been produced. In all cases these cross section data sets have been produced from an analysis of experimental data, even though there were significant discrepancies between different experiments for many transitions. Theoretical calculations have been largely excluded from critical evaluations of the data due to large uncertainties. This changed with the application of the convergent close-coupling (CCC) method to electron collisions with molecules.

In a new Topical Review published in EPJD, authors at Curtin University, Australia and Los Alamos National Laboratory, USA present a comparison of spherical- and spheroidal-coordinate formulations of the molecular convergent close-coupling method in calculating electron-impact excitation cross sections for molecular hydrogen, finding good agreement between the results of these two techniques. For the spheroidal-coordinate approach the adiabatic-nuclei method has been applied, allowing for more reliable estimate of cross sections at near-threshold energies. Comparison of the adiabatic-nuclei cross sections with the corresponding fixed-nuclei cross sections is also presented. This article is part of the Topical Issue on Low-Energy Positron and Positronium Physics and Electron-Molecule Collisions and Swarms (POSMOL 2019).