Quantum chemical approach for positron annihilation spectra of atoms and molecules beyond plane-wave approximation

Ikabata, Yasuhiro; Aiba, Risa; Iwanade, Toru; Nishizawa, Hiroaki; Wang, Feng; Nakai, Hiromi

doi:10.1063/1.5019805

Cited by 7 publications

(7 citation statements)

References 78 publications

(107 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Other areas for future investigation are calculations of binding energies for nitriles, alcohols, aldehydes, ketones, formates, and acetates, for which many binding energies are known from the measurements [29]. Calculations can also be extended to the annihilation γ -ray spectra, for which the experimental data [77] have only recently started to be investigated [78,79]. We have previously shown that the model-correlation-potential method can be used to calculate low-energy elastic scattering and direct annihilation rates for small nonpolar molecules [43], and it may be possible to also use the method to compute direct annihilation rates for polar molecules.…”

Section: Discussionmentioning

confidence: 99%

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

et al. 2021

View full text Add to dashboard Cite

Measured and calculated positron binding energies are presented for a range of hydrocarbons with up to six carbon atoms (viz., methane, acetylene, ethylene, ethane, propane, butane, and hexane) and their chlorinated counterparts. Both experiment and theory confirm the large effect that the chlorine atoms have on the positron binding energy and the strong sensitivity of the binding energy to the exact position of the chlorine atoms. The experimental binding energies have been obtained by measuring positron resonant annihilation using a trapbased positron beam. The calculations are performed using the previously developed model-correlation-potential method [A. R. Swann and G. F. Gribakin, J. Chem. Phys. 149, 244305 (2018)]. The overall trends are discussed with regard to the molecular polarizability, dipole moment, and geometry. Good agreement between theory and experiment is found, with the exception of the chlorinated ethylenes and chlorinated hexane. Calculations of the electron-positron annihilation rate in the bound state are also presented.

show abstract

Section: Discussionmentioning

confidence: 99%

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In addition to the annihilation rates, we will also use the bound-state positron wave functions to compute annihilation γ-ray spectra, where much of the experimental data 90 remained unexplained for a long time 91 and have only started to be explored now. 92…”

Section: Discussionmentioning

confidence: 99%

Calculations of positron binding and annihilation in polyatomic molecules

Swann

Gribakin

2018

The Journal of Chemical Physics

View full text Add to dashboard Cite

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 .

show abstract

“…It can also be used to make predictions for other molecular species, to guide future experimental effort and provide comparisons for more sophisticated quantum-chemistry calculations. The positron wave function can also be used to calculate the annihilation γ spectra, where much of the experimental data [41] still awaits theoretical analysis [50].…”

mentioning

confidence: 99%

Positron Binding and Annihilation in Alkane Molecules

Swann

Gribakin

2019

Phys. Rev. Lett.

View full text Add to dashboard Cite

A model-potential approach has been developed to study positron interactions with molecules. Binding energies and annihilation rates are calculated for positron bound states with a range of alkane molecules, including rings and isomers. The calculated binding energies are in good agreement with experimental data, and the existence of a second bound state for n-alkanes (C n H 2n+2 ) with n ≥ 12 is predicted in accord with experiment. The annihilation rate for the ground positron bound state scales linearly with the square root of the binding energy.

show abstract

Quantum chemical approach for positron annihilation spectra of atoms and molecules beyond plane-wave approximation

Cited by 7 publications

References 78 publications

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

Effect of chlorination on positron binding to hydrocarbons: Experiment and theory

Calculations of positron binding and annihilation in polyatomic molecules

Positron Binding and Annihilation in Alkane Molecules

Contact Info

Product

Resources

About