Positron lifetimes in metal hydrides

Gainotti, A.; Ghezzi, Carlo; Manfredi, M.; Zecchina, L.

doi:10.1007/bf02711952

Cited by 25 publications

(4 citation statements)

References 8 publications

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“…14 Second, HF 4 and Ho's best Hylleraas 14 gave 0.3 and 2.46 ns Ϫ1 , for the positron-electron two-photon annihilation rate, respectively. No experimental value for the two-photon annihilation rate of PsH has been given, but Gainotti 17 This estimated value is in good agreement with Ho's best Hylleraas, 14 whereas HF value is one order of magnitude smaller than the estimated one. This shows that the correlation cusp is very important for the two-photon annihilation rate, since this value is proportional to the electron density at the place of positron.…”

Section: Introductionmentioning

confidence: 70%

Application of pair correlation theory to positronium compounds

Saito

Sasaki

1995

The Journal of Chemical Physics

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Extension of weak orthogonality ͑WO͒ techniques developed by Szalewicz et al. and coupled pair equations derived by Jeziorski et al. to positronium compounds are presented. These methods enable us to calculate many-electronic positronium compounds with explicitly correlated functions. These methods were applied to positronium hydride ͑PsH͒ with Hylleraas-type functions ͑HTF's͒, and the total energies, the positron-electron two-photon annihilation rates, and the positronium binding energies were calculated. Extended coupled pair equations were solved by CEPA͑2͒-type, complete coupled pair ͑CCP͒ procedures, and independent pair approximation ͑IPA͒ of CCP. For the total energies, IPA, CEPA͑2͒, and CCP procedures gave Ϫ0.78899, Ϫ0.78238, and Ϫ0.77471 au, respectively. For the two-photon annihilation rates, the respective procedure gave 2.088, 2.064, and 1.972 ns Ϫ1 , respectively.

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Section: Introductionmentioning

confidence: 70%

Application of pair correlation theory to positronium compounds

Saito

Sasaki

1995

The Journal of Chemical Physics

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“…Hydrogen can interact with different complexes, including vacancy-type defects, impurity atoms, dislocations, intrinsic interstitial atoms, and grain boundaries [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. In addition, hydrogen actively interacts with existing structural defects and induces the formation of many new defects [ 10 , 11 , 12 , 13 , 14 , 15 ]. The mechanisms of hydrogen’s effect on defects and the structural-phase state and mechanical properties of metallic materials have not been fully established despite numerous studies in this area.…”

Section: Introductionmentioning

confidence: 99%

“…The effectiveness of positron spectroscopy for studying and monitoring metal–hydrogen systems has been demonstrated in many works [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. However, there remain significant limitations associated with the impossibility of directly studying the evolution of the defect structure in the processes of absorption, accumulation, and distribution of hydrogen, despite the recent appearance of positron spectrometers and spectrometric complexes with high technical characteristics.…”

Section: Introductionmentioning

confidence: 99%

Positron Annihilation Spectroscopy Complex for Structural Defect Analysis in Metal–Hydrogen Systems

et al. 2022

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The current work is devoted to developing a system for the complex research of metal–hydrogen systems, including in an in situ mode. The system consists of a controlled gas reactor with a unique reaction chamber, a radioisotope positron source, and a positron annihilation spectroscopy complex. The use of the system enables in situ investigation of the defect structure of solids in hydrogen sorption–desorption processes at temperatures up to 900 °C and pressures up to 50 bar. Experimental investigations of magnesium and magnesium hydride during thermal annealing were carried out to approve the possibilities of the developed complex. It was shown that one cycle of magnesium hydrogenation–dehydrogenation resulted in the accumulation of irreversible hydrogen-induced defects. The defect structure investigation of the magnesium–hydrogen system by positron annihilation techniques was supplemented with a comprehensive study by scanning electron microscopy, X-ray diffraction analysis, and hydrogen sorption–desorption studies.

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“…The present work and that of Bressanini et al 10 13 and 2.35Ϯ0.15 ns Ϫ1 in a sequence of alkali-metal hydrides, extrapolated to the zero density limit. 14 Both the binding energy and the annihilation rate are of some interest from the points of view of fundamental and computational physics. The calculation of each quantity requires a very accurate description of the correlated motion of the annihilating particles.…”

Section: Introductionmentioning

confidence: 99%

Diffusion quantum Monte Carlo calculation of the binding energy and annihilation rate of positronium hydride, PsH

Jiang

Schrader

1998

The Journal of Chemical Physics

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Using the diffusion quantum Monte Carlo ͑DMC͒ method with importance sampling, we calculate the binding energy and annihilation rate of positronium hydride, PsH. We get 1.0661Ϯ0.0014 eV for the binding energy, and 2.463Ϯ0.020 ns Ϫ1 for the annihilation rate. The binding energy is in agreement with the results of the best Ritz variational calculations and the best DMC calculation reported to date, and the annihilation rate agrees with the results of the Ritz variational calculations but not that of the only other DMC result known to us. A new method for correcting expectation values calculated from mixed estimators is proposed and demonstrated.

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Positron lifetimes in metal hydrides

Cited by 25 publications

References 8 publications

Application of pair correlation theory to positronium compounds

Application of pair correlation theory to positronium compounds

Positron Annihilation Spectroscopy Complex for Structural Defect Analysis in Metal–Hydrogen Systems

Diffusion quantum Monte Carlo calculation of the binding energy and annihilation rate of positronium hydride, PsH

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