A Generalized Single Centre Approach for Treating Electron Scattering from Polyatomic Molecules

Gianturco, F. A.; Lucchese, Robert R.; Sanna, Nico; Talamo, Alberto

doi:10.1007/978-1-4899-1489-7_6

Cited by 25 publications

(24 citation statements)

References 24 publications

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“…We have shown that the treatment of such forces in the intermediate range of distances is a crucial element of the model and that we can test this region in a parameter-free fashion by using either of the possible crossing radii between the DFT-SR forces and the LR-polarisation potential. The present calculations indeed show that, contrary to what has been found for electron collisions [13,16,33], the scattering processes with positron projectiles invariably require a stronger intermediate-range potential and therefore are better described by choosing the outer cut-off radii as matching distances within the LYP formulation of the correlation forces. In other words, the present DFT model allows one to make a distinction, as is physically expected, between correlation effects from either electron or positron collisions by using a stronger DFT model of correlation forces for the latter as opposed to the former projectile.…”

Section: Discussioncontrasting

confidence: 57%

“…This suggests that a more realistic choice for positron scattering when modelling the correlation forces comes from selecting the LYP form of local DFT correlation and polarisation potentials, as was found to be the case of electron scattering studies [33].…”

Section: The Integral Elastic Cross Sectionsmentioning

confidence: 98%

“…An analogous discrepancy appears for the N2 molecule, where both choices of cut-off within the LYP treatment of Vop do not exhibit any cross section minimum at low energies. We know that the presence of cross section minima at low collision energies is related, from the theoretical standpoint, to a delicate balance of attractive and repulsive branches in the overall, local scattering potential [33] as function of the relative collision energy. The choice of the leading terms in the multipolar expansion of the present interactions is therefore a very important element for obtaining such minima and for locating them at the correct energy positions.…”

Section: The Integral Elastic Cross Sectionsmentioning

confidence: 99%

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Polarisation potentials for positron-molecule scattering processes

Gianturco¹,

Paioletti²,

Rodriguez-Ruiz

1996

Z Phys D - Atoms, Molecules and Clusters

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Abstract.A new form of a local, model polarisationcorrelation potential obtained via Density Functional Theory (DFT) is proposed for the treatment of positron scattering from Hz and N2 molecules at energies below the threshold of positronium formation. The derivation of the potential is briefly discussed and its relative importance for the elastic channels of the scattering process is analysed in detail.Final elastic cross sections, rotationally summed, are compared with experiments and with existing theoretical results. They are found to agree reasonably well with measurements and suggest the present model as a useful, and simple, method for treating short-range correlation forces in positron scattering calculations for molecular systems.

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Section: Discussioncontrasting

confidence: 57%

Section: The Integral Elastic Cross Sectionsmentioning

confidence: 98%

Section: The Integral Elastic Cross Sectionsmentioning

confidence: 99%

See 1 more Smart Citation

Polarisation potentials for positron-molecule scattering processes

Gianturco¹,

Paioletti²,

Rodriguez-Ruiz

1996

Z Phys D - Atoms, Molecules and Clusters

Self Cite

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“…This method has been discussed in detail previously and will not be discussed further here. 35,39,40 In all matrix elements, the wave functions were expanded up to a partial wave of l max ϭ20 and all terms were retained in the expansions of the static and exchange integrals consistent with this value of l max . All calculations were done with the C atom as the FIG.…”

Section: B Calculated Resultsmentioning

confidence: 99%

Excitation of the symmetry forbidden bending mode in molecular photoionization

Miller

Poliakoff

Miller

et al. 2001

The Journal of Chemical Physics

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We present results on the energy dependence of the vibrational branching ratio for the bending mode in CO 2 3 u Ϫ1 photoionization. Specifically, we determine the v ϩ ϭ(0,1,0)/v ϩ ϭ(0,0,0) intensity ratio by detecting dispersed fluorescence from the electronically excited photoions. The results exhibit large deviations over a very wide energy range, 18Ͻh exc Ͻ190 eV. Production of the v ϩ ϭ(0,1,0) level of the ion from the v 0 ϭ(0,0,0) ground state is forbidden by symmetry, and while observations of such features are well established in photoelectron spectroscopy, their appearance is normally ascribed to vibronic coupling in the ionic hole state. In this case, we find that such explanations fail to account for the energy dependence of the branching ratio. These deviations indicate that the continuum photoelectron participates in transferring oscillator strength to the nominally forbidden vibrational transition. A theoretical framework is developed for interpreting the experimental data, and Schwinger variational calculations are performed. These calculations demonstrate that the continuum electron is responsible for the observation of the excited bending mode as well as its energy dependence. This is an intrachannel effect that is best described as photoelectron-induced vibronic symmetry breaking. This appears to be a general phenomenon, and it may be useful in illuminating connections between bond angle and photoionization spectroscopies. The magnitude of these deviations display the utility of vibrationally resolved studies, and the extent over which these changes occur underscores the necessity of broad range studies to elucidate slowly varying characteristics in photoionization continua.

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“…Details of the basic theory employed to describe the scattering process have been presented previously (Gianturco et al 1994) and therefore we only give a brief outline of it here.…”

Section: The Single-centre Expansionmentioning

confidence: 99%

Low-energy electron scattering and resonant states of NO₂( X²A₁)

Čurík

Gianturco

Lucchese

et al. 2000

J. Phys. B: At. Mol. Opt. Phys.

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We present new calculations of the integral elastic cross sections for electron scattering from NO 2 in its ground electronic state and we also discuss the spatial shapes of its low-energy single-particle resonances. The integral cross sections are obtained as a weighted sum of the singlet and triplet scattering processes and show fair agreement with the existing experiments. The resonant states are analysed via a local model potential discussed here and the results clearly show the feasibility of interpreting known experimental features of NO 2 dissociative attachment, and its similarities with the e − -O 3 data, in terms of the spatial shapes of the metastable single-particle scattering resonances obtained from our calculations.

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A Generalized Single Centre Approach for Treating Electron Scattering from Polyatomic Molecules

Cited by 25 publications

References 24 publications

Polarisation potentials for positron-molecule scattering processes

Polarisation potentials for positron-molecule scattering processes

Excitation of the symmetry forbidden bending mode in molecular photoionization

Low-energy electron scattering and resonant states of NO₂( X²A₁)

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A Generalized Single Centre Approach for Treating Electron Scattering from Polyatomic Molecules

Cited by 25 publications

References 24 publications

Polarisation potentials for positron-molecule scattering processes

Polarisation potentials for positron-molecule scattering processes

Excitation of the symmetry forbidden bending mode in molecular photoionization

Low-energy electron scattering and resonant states of NO2( X2A1)

Contact Info

Product

Resources

About

Low-energy electron scattering and resonant states of NO₂( X²A₁)