Probing the nonlocal approximation to resonant collisions of electrons with diatomic molecules

Abstract

A numerically solvable two-dimensional model introduced by the authors [Phys. Rev. A 73, 032721 (2006)] is used to investigate the validity of the nonlocal approximation to the dynamics of resonant collisions of electrons with diatomic molecules. The nonlocal approximation to this model is derived in detail, all underlying assumptions are specified and explicit expressions for the resonant and non-resonant (background) T matrix for the studied processes are given. Different choices of the so-called discrete state, which fully determines the nonlocal approximation, are discussed and it is shown that a physical choice of this state can in general give poorer results than other choices that minimize the non-adiabatic effects and/or the background terms of the T matrix. The background contributions to the cross sections, which are usually not considered in the resonant theory of electron-molecule collisions, can be significant not only for elastic scattering but also for the inelastic process of vibrational excitation.

Dissociative electron attachment to halogen molecules: Angular distributions and nonlocal effects

“…At E < 0.4 eV the local theory results are substantially lower than nonlocal, except the low-energy region below 0.03 eV where the calculations without Bardsley correction exhibit the 1/E divergence. Similar results for DEA to the F 2 molecule were obtained by Houfek et al [40]: their local cross sections for the "F 2 -like model" are substantially smaller than nonlocal in the energy interval between 0.03 and 0.6 eV. It is also interesting that the exact cross sections obtained within the framework of their model are close to the results of the nonlocal theory whose only assumption is the Born-Oppenheimer approximation.…”

Theoretical vibrational-excitation cross sections and rate coefficients for electron-impact resonant collisions involving rovibrationally excited N2and NO molecules

“…NO − contributes to process (2) with the three resonant electronic states 3 Σ − , 1 ∆, 1 Σ + , while process (1) proceeds through the resonant X 2 Π g state, responsible for the well-known 2.3 eV resonance peak in electron-N 2 collision experiments [5]. Experimental measurements [5,6,7,8,9,10,11,12] and theoretical calculations [13,14,15,16,17,18,19,20] of cross sections exist in literature for the above processes. However, despite the broad production of cross sections data, especially for nitrogen, all the previous works are restricted to excitations between the first few vibrational levels.…”

Dissociative recombination by frame transformation to Siegert pseudostates: A comparison with a numerically solvable model

“…For the latter we choose to provide numerical evidence by comparing the results with benchmark data which are obtained with a numerically solvable model of H + 2 in two dimensions, with one electronic and one nuclear coordinate. The model is similar to the two-dimensional model of resonant electron-molecule collisions, which was introduced in [15] and used to test the local and nonlocal theory of nuclear dynamics of these collisions [15,16].…”

“…of (41) clearly represents a portion of the total wave function in which the electron is described by a combination of the exponentially decaying functions with the nuclear components having the outgoing-wave boundary conditions, at present we are not able to recast this term into Eq. (16) in which the electronic energies are discrete (atomic Rydberg states) and the nuclear energies are continuous (nuclear kinetic energy release).…”