Many-Body Theory for Positronium-Atom Interactions

Green, D. G.; Swann, A. R.; Gribakin, G. F.

doi:10.1103/physrevlett.120.183402

Cited by 25 publications

(24 citation statements)

References 45 publications

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“…where dτ is the volume element associated with r . The correlation potential V cor can be derived using many-body theory [9,[44][45][46][47][48][49], or approximated using density-functional-theory approaches, based on the positron correlation energy in an electron gas and correct long-range asymptotic form [50,51]. It can also be represented by a model potential with correct long-range behavior and parametrized form at short range.…”

Section: A Schrödinger Equation For Positronmentioning

confidence: 99%

Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules using a Gaussian basis

Swann

Gribakin

2020

Phys. Rev. A

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A model-potential method is employed to calculate binding, elastic scattering, and annihilation of positrons for a number of atoms and small nonpolar molecules, namely, Be, Mg, He, Ar, H 2 , N 2 , Cl 2 , and CH 4 . The model potential contains one free parameter for each type of atom within the target. Its values are chosen to reproduce existing ab initio positron-atom binding energies or scattering phase shifts. The calculations are performed using a Gaussian basis for the positron states, and we show how to obtain values of the scattering phase shifts and normalized annihilation rate Z eff from discrete positive-energy pseudostates. Good agreement between the present results and existing calculations and experimental data, where available, is obtained, including the Z eff value for CH 4 , which is strongly enhanced by a low-lying virtual positron state. An exception is the roomtemperature value of Z eff for Cl 2 , for which the present value is much smaller than the experimental value obtained over 50 years ago. Our calculations predict that among the molecular targets studied, only Cl 2 might support a bound state for the positron, with a binding energy of a few meV.

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Section: A Schrödinger Equation For Positronmentioning

confidence: 99%

Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules using a Gaussian basis

Swann

Gribakin

2020

Phys. Rev. A

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“…for He and 1.76 a.u. for Ne, of Green et al[16]. They are slightly larger than the recommended values of ref [11],.…”

mentioning

confidence: 59%

“…In Fig. 6 we show the momentum transfer cross sections for Ps scattering by He and Ne compared with the many body theory calculations of [16] and various experimental swarm…”

Section: Ps Scattering By He and Nementioning

confidence: 99%

“…Other recent calculations in which the Ps-atom system is enclosed in a hard spherical wall have also led to larger cross sections below the ionization threshold for Rg atoms [11]. A number of other calculations [12][13][14][15][16] for Ps scattering by the Rg atoms have been done and these have been summarized in ref. [11].…”

Section: Introductionmentioning

confidence: 99%

“…It appears that there is some discrepancy between experiment and theory for Ps scattering by Rg atoms below the ionization threshold. On the other hand, recent calculations [11,16] indicate that perhaps previous pseudopotential calculations [9] overestimate the Ps cross section in the low-energy energy region, and more calculations, incorporating more accurately exchange and correlations, are required.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Positronium collisions with rare-gas atoms: Free-electron gas plus orthogonalizing pseudopotential model

Wilde

Fabrikant

2018

Phys. Rev. A

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Positronium collisions with rare-gas atoms are treated using the free-electron-gas approximation for exchange and correlation potential. The results confirm the absence of the Ramsauer-Townsend minimum in elastic scattering cross sections, but show lower cross sections in the lower-energy region when compared to previous pseudopotential calculations. This is explained by a more attractive ab initio correlation potential as compared to the previously used empirical potential. The results in the thermal energy region agree very well with most swarm measurements for all rare gas atoms. At higher energies the results are compared with beam experiments, and agreement for heavier rare gas atoms, Ar, Kr and Xe, is found to be very good. For He and Ne some discrepancies wth beam measurements are observed. This is explained by a poorer performance of the free electron gas potentials, based on the statistical Thomas-Fermi model, for systems with fewer electrons.

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BSHF: A program to solve the Hartree–Fock equations for arbitrary central potentials using a B-spline basis

Waide

Green

Gribakin

2020

Computer Physics Communications

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Many-Body Theory for Positronium-Atom Interactions

Cited by 25 publications

References 45 publications

Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules using a Gaussian basis

Model-potential calculations of positron binding, scattering, and annihilation for atoms and small molecules using a Gaussian basis

Positronium collisions with rare-gas atoms: Free-electron gas plus orthogonalizing pseudopotential model

BSHF: A program to solve the Hartree–Fock equations for arbitrary central potentials using a B-spline basis

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