Single-center approach for photodetachment and radiative electron attachment: Comparison with other theoretical approaches and with experimental photodetachment data

Abstract

A single-center method for calculating photodetachment cross section for anions and radiative electron attachment cross section for neutral molecules by microreversibility is presented. It uses the integral equation method to calculate the ejected electron's continuum wave function while the single-electron bound function of the anion is described by the Dyson orbital. It is compared with related theoretical approaches and benchmarked to the experimental photodetachment cross sections of O 2 − , OH − , and CN − . The use of the plane-wave approximation of the ejected electron wave function combined with the Hartree-Fock frozen-core approximation of the Dyson orbital is also considered and its results are compared with those of our methods and with experiment. A good agreement between the calculated photodetachment cross sections and the experimental data is obtained for O 2 − and CN − when using the three methods. For OH − , the calculated scattering-wave electron photodetachment cross sections agree well with two most recent sets of experimental data among the three available while the plane-wave results disagree with all the experimental and theoretical data. The different approaches to calculate the Dyson orbital are also discussed as well as the convergence of the calculations with respect to the choice of the one-electron basis set. The approximation of Dyson orbitals by Kohn-Sham orbitals appears to overestimate the photodetachment cross section.

Radiative Electron Attachment and Photodetachment Rate Constants for Linear Carbon Chains

“…The Dyson orbitals have been extracted from the ground state CASSCF wavefunctions of the anions and the corresponding neutral molecules. 30 If ψ N ( r 1 , r 2 , . .…”

“…where N 0 is the product of the spin and electronic degeneracy factor, 30 Ψ lm (r) is the wave function of the outgoing electron, and Ψ d (r) is the Dyson orbital. Let us recall that the Dyson orbital 38,39 is a molecular orbital which represents the change of the molecular electronic configuration induced by electron attachment or by photodetachment.…”

Low-lying Dipole Resonances in FeCN−: A Viable Formation Pathway for FeCN− in Space

“…However, the pathways for the formation of anions by electron attachment face restrictions in the low-density ISM where three-body collisions to dispose of the excess energy are not plausible. Radiative electron attachment (REA) to neutral species is considered to form anions in the ISM (Chandrasekaran et al 2017;Douguet et al 2013;Lara-Moreno et al 2019a, 2019b. REA cross sections could be enhanced in molecules with permanent dipole moment above the critical value of 1.65 D, since they could accommodate dipole-bound anion states (DBS) that lie below but close to the detachment threshold (Garrett 1982;Anstöter et al 2020).…”

Direct observation of long-lived cyanide anions in superexcited states

“…Its productions by the REA to CN radical, the DEA to cyanopolyynes HC n N (n = 1-3) or MgCN/MgNC, and the H − + HC n N reactions were evaluated with modeling calculations 1,[4][5][6][7][8][9][10] . However, the role of REA process, initially proposed as the dominant mechanism 4 , is still open to the debate [8][9][10][11][12][13] , in particular, the CN − abundance in IRC + 10216 predicted with statistics theory calculations indicated a significant deviation from the observation 8,13 . Recently, the contribution from the DEA to H 2 CN in IRC + 10216 was eliminated either 14 .…”

“…Furthermore, the CN − (X 1 Σ + ) can be stabilized in various vibrational states (ν) up to ν = 17, while that in the higher ν-state is believed to quickly decay via vibrationinduced electron detachment 16 . Therefore, the vibrationally or electronically excited states above the electron autodetachment threshold of CN − , namely, those locate 3.862 eV (EA) higher than X 1 Σ + (ν = 0), are assumed to have no contributions to the CN − abundance and some chemical reactions in the interstellar space 1,[4][5][6][7][8][9][10][11][12][13] . However, a long-lived anion in high-lying excited states can be observed, if its vibration-induced electron detachment proceeds in a non-negligible time, for instance, on a timescale comparable to the lifetimes (such as the nanoseconds to microseconds of LiH − and OH − , ref.…”