Scattering of Electrons by Hydrogenic Ions.

The Algebraic Variational method in Atomic physics is applied for the first time to the scattering (both elastic and inelastic) of electrons by highly stripped (hydrogenic) atomic ions. The overall behavior of the excitation 1s (---\u3e) 2s and 1s (---\u3e) 2p cross section is investigated using a 6 state expansion (1s-2s-2p one and two p pseudo-states) of the target wave function. The close coupling calculation is carried out up to a total angular momentum L(,MAX), (L(,MAX) (LESSTHEQ) 5) and for energies ranging from just above the n = 2 threshold to 5 times threshold; otherwise the Coulomb Born approximation with exchange is used. The computed collision strengths are then fit by an analytic formula. Finally, using a large pseudostate set, resonances between the n = 2 and n = 3 thresholds are investigated and accurately traced. Resonance enhancement of excitation rates is discussed. Results are reported for electron scattering by C(\u275+) and O(\u277+). Comparison is made to other theoretical calculations

Quantum-Mechanical Calculations of Cross Sections for Electron Collisions With Atoms and Molecules

An overview of quantum‐mechanical methods to generate cross‐section data for electron collisions with atoms and molecules is presented. Particular emphasis is placed on the time‐independent close‐coupling approach, since it is particularly suitable for low‐energy collisions and also allows for systematic improvements as well as uncertainty estimates. The basic ideas are illustrated with examples for electron collisions with argon atoms and methane. For many atomic systems, such as e‐Ar collisions, highly reliable cross sections can now be computed with quantified uncertainties. On the other hand, while electron collision calculations with molecules do provide key input data for plasma models, the methods, and computer codes presently used require further development to make these inputs robust

Comparison of multichannel and two-state calculations for H-atom transfer between two nearly degenerate states

Multichannel and two-state calculations are made for a collinear H-atom transfer between two heavy masses. The particular reaction studied is on where the initial vibrational state of the reactants is nearly degenerate with a vibrational state of the products. The two sets of results for the reaction probability are in good agreement with each other