One-electron resonances and computed cross sections in electron scattering from the benzene molecule

Abstract

One-electron resonances arising in electron scattering processes from a nonlinear polyatomic target, the benzene molecule, have been examined using various related methods. First, we have carried out calculations over a broad range of collision energies ͑from about 0.001 eV up to about 30 eV͒ by solving the scattering equations which use a parameter-free exact-static-exchangeplus-correlation-polarization potential to treat the electron-molecule interaction in all scattering symmetries. The entire range of features produced by the calculations was then related to specific structural properties of the scattering functions which give rise to the resonances. This analysis was done by using wave functions obtained with a local model potential approximation to the full potential used in the scattering calculations. These scattering functions were also related to the virtual orbitals obtained from a minimum basis set self-consistent field calculation. Additionally, for each resonant state found in this study we related the energy and width of the resonance to the partial wave components of the nearly adiabatic potential energy curve of the appropriate symmetry generated from the local model potential.

A study of electron scattering from benzene: Excitation of the 1B1u, 3E2g, and 1E1u electronic states

“…Finally, we note the total ionization cross section results from measurements due to Schram et al 29 From a theoretical perspective, elastic electron scattering from C 6 H 6 , at energies up to about 40 eV, using single-center expansion methods at the static exchange level, were reported by Gianturco and Lucchese. 30 Elastic data were also reported by Bettega et al, 31 although in this case the Schwinger multichannel method at both the static exchange and static exchange plus polarization levels was utilized. Ma et al, 32 using an independent atom model approach, reported elastic differential cross sections (DCSs), integral cross sections (ICSs) and momentum transfer cross sections for e − -C 6 H 6 scattering in the 100-1000 eV range.…”

Theoretical and experimental study on electron interactions with chlorobenzene: Shape resonances and differential cross sections

“…10 There are at least two previous works available in the literature reporting cross sections for low-energy electron scattering by benzene. 50,51 Especially, we highlight the ab initio calculation performed by Bettega et al, 50 also using the SMC method, which placed the π * resonances at 2.23 eV and 8.39 eV, with the first resonance being double degenerate. In this work, we see that the breakage of symmetry due to the chlorine atom "splits" the first resonance of benzene into two, as expected, even though the experimental data are unable to observe this.…”

Elastic scattering of low-energy electrons by benzene

“…Sueoka 1 and Mozejko et al 2 have measured total cross sections for a very broad energy range. Gianturco and Lucchese 3 have computed integral, differential, and partial ͑by symmetry͒ elastic cross sections using a parameter-free exact-static-exchange-plus-correlation-polarization potential. They have found several shape resonances: one in the E 2u representation, located at 1.82 eV; another in B 2g , located at 7.44 eV; a third in E 1u , located at 10.07 eV; and a fourth in A 2g , located at 21.17 eV.…”

“…Benzene is an intrinsically interesting target molecule due to its geometry and symmetry and is of additional interest in light of recent experimental and theoretical studies. [1][2][3][10][11][12] Our calculations employed the Schwinger multichannel ͑SMC͒ method 17,18 as implemented for parallel computers 19 and were carried out both in the static-exchange and in the static-exchange-plus-polarization ͑SEP͒ approximations. This study may be considered a first step toward studies of more complex aromatic molecules such as the fluoro-, chloro-, and fluorochlorobenzenes 20 or the DNA bases.…”