Relativistic linearized coupled-cluster single-double calculations of positron-atom bound states

Dzuba, V. A.; Flambaum, V. V.; Gribakin, G. F.; Harabati, C.

doi:10.1103/physreva.86.032503

Cited by 21 publications

(31 citation statements)

References 55 publications

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“…Consideration of this system was motivated by an extant discrepancy, that the measured recombination cross section was much larger than those predicted by very extensive calculations [17], particularly close to the ionization threshold (i.e., for low incident electron energies). Use of a statistical description of the compound resonances resolved the discrepancy [11,18]. A similar enhancement of the recombination due to compound resonances was found earlier in the isoelectric ion Au 25+ [19] and explained by the statistical theory [5].…”

Section: Introductionmentioning

confidence: 49%

“…The energy ε αβγ −1 is the energy for the resonance (relative to the W 19+ ionization threshold). In [5,11] the resonance energy used is the single-particle energy ε αβγ −1 = ε α + ε β − ε γ , while in this work we present our configuration-averaged statistical theory using the configuration-averaged energy of a relativistic configura-…”

Section: B Configuration-averaged Statistical Theorymentioning

confidence: 99%

“…A full exploration of the statistical properties of the mixing coefficients C (ν) k can be found in [11].…”

Section: A Statistical Theory Of Electron Capture Into Compound Resomentioning

confidence: 99%

“…Earlier statistical theories [5,11,18] treated this problem by combining a many-body theory approach for the calculation of the amplitude for the two active electrons to populate various single-particle orbitals, with the idea of spreading of the two-electron states into chaotic manyelectron eigenstates (i.e., compound resonances). The latter process was parameterized through its rate (known as the spreading width Γ spr ), that was estimated by constructing limited configuration-interaction Hamiltonian matrices.…”

Section: Introductionmentioning

confidence: 99%

“…Earlier papers [7,8] and reviews [9,10] present the development of the statistical theory for the matrix elements between chaotic compound states. This theory enables one to calculate mean values of orbital occupation numbers, squared electromagnetic amplitudes, electronic and electromagnetic widths and enhancement of weak interactions in chaotic excited states of nuclei, atoms and multicharged ions [3][4][5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

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Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

et al. 2015

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The strong mixing of many-electron basis states in excited atoms and ions with open f shells results in very large numbers of complex, chaotic eigenstates that cannot be computed to any degree of accuracy. Describing the processes which involve such states requires the use of a statistical theory. Electron capture into these 'compound resonances' leads to electron-ion recombination rates that are orders of magnitude greater than those of direct, radiative recombination, and cannot be described by standard theories of dielectronic recombination. Previous statistical theories considered this as a two-electron capture process which populates a pair of single-particle orbitals, followed by 'spreading' of the two-electron states into chaotically mixed eigenstates. This method is similar to a configuration-average approach, as it neglects potentially important effects of spectator electrons and conservation of total angular momentum. In this work we develop a statistical theory which considers electron capture into 'doorway' states with definite angular momentum obtained by the configuration interaction method. We apply this approach to electron recombination with W 20+ , considering 2 million doorway states. Despite strong effects from the spectator electrons, we find that the results of the earlier theories largely hold. Finally, we extract the fluorescence yield (the probability of photoemission and hence recombination) by comparison with experiment.

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Section: Introductionmentioning

confidence: 49%

Section: B Configuration-averaged Statistical Theorymentioning

confidence: 99%

“…A full exploration of the statistical properties of the mixing coefficients C (ν) k can be found in [11].…”

Section: A Statistical Theory Of Electron Capture Into Compound Resomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

et al. 2015

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Excited S-symmetry states of positronic lithium and beryllium

Strasburger

2016

The Journal of Chemical Physics

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The possibility of the existence of excited S-symmetry states of positronic lithium and beryllium, resulting from the positron attachment to high-spin P parent atomic states, is examined and confirmed with variational calculations in the basis of explicitly correlated Gaussian functions. The unexpectedly different order of the energies of the S and P states is explained by the formation of the positronium cluster structure and associated disappearance of the destabilizing centrifugal force. The annihilation properties of newly discovered states are discussed in the context of prospective experimental detection.

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Calculations of positron binding and annihilation in polyatomic molecules

Swann

Gribakin

2018

The Journal of Chemical Physics

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A model-potential approach to calculating positron-molecule binding energies and annihilation rates is developed. Unlike existing ab initio calculations, which have mostly been applied to strongly polar molecules, the present methodology can be applied to both strongly polar and weakly polar or nonpolar systems. The electrostatic potential of the molecule is calculated at the Hartree-Fock level, and a model potential that describes short-range correlations and long-range polarization of the electron cloud by the positron is then added. The Schrödinger equation for a positron moving in this effective potential is solved to obtain the binding energy. The model potential contains a single adjustable parameter for each type of atom present in the molecule. The wave function of the positron bound state may be used to compute the rate of electron-positron annihilation from the bound state. As a first application, we investigate positron binding and annihilation for the hydrogen cyanide (HCN) molecule. Results for the binding energy are found to be in accord with existing calculations, and we predict the rate of annihilation from the bound state to be Γ = 0.1-0.2 × 10 9 s −1 .

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Relativistic linearized coupled-cluster single-double calculations of positron-atom bound states

Cited by 21 publications

References 55 publications

Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

Level-resolved quantum statistical theory of electron capture into many-electron compound resonances in highly charged ions

Excited S-symmetry states of positronic lithium and beryllium

Calculations of positron binding and annihilation in polyatomic molecules

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