Cross sections for electron-impact excitation of the H<sub>2</sub>molecule using the MOB-SCI strategy

Costa, Romarly F. da; Paixão, Fernando; Lima, Marco A. P.

doi:10.1088/0953-4075/38/24/003

Cited by 63 publications

(83 citation statements)

References 55 publications

(162 reference statements)

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“…The first attempt to investigate the influence of the multichannel coupling effect in electron-molecule collisions, through the use of the MOBSCI strategy, involved the study of the electronic excitation (from the ground state to the lowest lying triplet and singlet states) of H 2 [38,128] and N 2 [129,130] by electron impact. In both cases, for a particular excitation process, the open channel space was composed by the ground state, by the first triplet and singlet states of a given symmetry (more specifically, the symmetry of the excited state involved in the transition) and by the pseudo states arising from the SCI description of the target.…”

Section: Electronic Excitation and Elastic Scattering Under The Influmentioning

confidence: 99%

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

et al. 2015

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Abstract. The Schwinger multichannel method [K. V. McKoy, Phys. Rev. A 30, 1734 (1984)], which is based on the Schwinger variational principle for the scattering amplitude [J. Schwinger, Phys. Rev. 72, 742 (1947)], was designed to account for exchange, polarization and electronically multichannel coupling effects in the low-energy region of electron scattering from molecules with arbitrary geometry. The applications of the method became more ambitious with the availability of computer power combined with parallel processing, use of norm-conserving pseudopotentials and improvement of the description of target excited states (minimal orbital basis for single configuration interaction). The most recent applications involving 33 and 45 electronically open channels for phenol and ethylene molecules, represent good examples of the present status of the method. In this colloquium, we review the strategy and point out new directions to apply the method in its full extension.

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Section: Electronic Excitation and Elastic Scattering Under The Influmentioning

confidence: 99%

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

et al. 2015

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“…18 Since the SMC method has been described in details in several publications, here we will only provide the relevant points for the present calculations.…”

Section: Computational Detailsmentioning

confidence: 99%

Shape resonances in low-energy-electron collisions with halopyrimidines

Barbosa

Bettega

2013

The Journal of Chemical Physics

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We report calculated cross sections for elastic collisions of low-energy electrons with halopyrimidines, namely, 2-chloro, 2-bromo, and 5-bromopyrimidine. We employed the Schwinger multichannel method with pseudopotentials to compute the cross sections in the static-exchange and static-exchange plus polarization levels of approximation for energies up to 10 eV. We found four shape resonances for each molecule: three of π* nature localized on the ring and one of σ* nature localized along the carbon-halogen bond. We compared the calculated positions of the resonances with the electron transmission spectroscopy data measured by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)]. In general the agreement between theory and experiment is good. In particular, our results show the existence of a π* temporary anion state of A2 symmetry for all three halopyrimidines, in agreement with the dissociative electron attachment spectra also reported by Modelli et al. [J. Phys. Chem. A 115, 10775 (2011)].

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“…1, on the other hand, was obtained Our calculations were performed in the static-exchange (SE) and in the static-exchange plus polarization (SEP) approximations. The scattering amplitudes are obtained within the minimal orbital basis for single configuration interactions (MOB-SCI) approach [35] for electron impact energies up to 50 eV. To represent polarization effects we considered single excitations from the occupied molecular orbitals to a set of modified virtual orbitals (MVO's) [36] obtained through the diagonalization of a Fock operator of a cation with charge +2.…”

Section: Theoreticalmentioning

confidence: 99%

“…The numerical stability of the calculations presented in this paper was checked with the procedure developed by Chaudhuri and co-workers, as adapted to electron-molecule scattering problem [35]. This procedure has been successfully applied to the analysis of spurious structures arising from numerical linear dependence among basis set functions in a series of recent applications of the SMC method.…”

Section: Theoreticalmentioning

confidence: 99%

Low-energy elastic electron scattering from furan

et al. 2010

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We report normalized experimental and theoretical differential cross sections for elastic electron scattering by C 4 H 4 O (furan) molecules from a collaborative project between several Brazilian theoretical groups and an experimental group at California State Fullerton, USA. The measurements are obtained by using the relative flow method with helium as the standard gas and a thin aperture target gas collimating source. The relative flow method is applied without the restriction imposed by the relative flow pressure condition on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 1.5, 1.73, 2, 2.7, 3, 5, 7, 10, 20, 30, and 50 eV and covered the angular range between 10 • and 130 • . The measurements verify observed π * shape resonances at 1.65 ± 0.05eV and 3.10 ± 0.05 eV scattering energies, in good agreement with the transmission electron data of Modelli and Burrow [J. Phys. Chem. A 108, 5721 (2004)]. Furthermore, the present results also indicated both resonances dominantly in the d-wave channel. The differential cross sections are integrated in the standard way to obtain integral elastic cross sections and momentum transfer cross sections. The calculations employed the Schwinger multichannel method with pseudopotentials and were performed in the static-exchange and in the static-exchange plus polarization approximations. The calculated integral and momentum transfer cross sections clearly revealed the presence of two shape resonances located at 1.95 and 3.56 eV and ascribed to the B 1 and A 2 symmetries of the C 2v point group, respectively, in very good agreement with the experimental findings. Overall agreement between theory and experiment regarding the differential, momentum transfer, and integral cross sections is very good, especially for energies below 10 eV.

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Cross sections for electron-impact excitation of the H₂molecule using the MOB-SCI strategy

Cited by 63 publications

References 55 publications

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

Shape resonances in low-energy-electron collisions with halopyrimidines

Low-energy elastic electron scattering from furan

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Cross sections for electron-impact excitation of the H2molecule using the MOB-SCI strategy

Cited by 63 publications

References 55 publications

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

Recent advances in the application of the Schwinger multichannel method with pseudopotentials to electron-molecule collisions

Shape resonances in low-energy-electron collisions with halopyrimidines

Low-energy elastic electron scattering from furan

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Cross sections for electron-impact excitation of the H₂molecule using the MOB-SCI strategy