Bound states of the positron with nitrile species with a configuration interaction multi-component molecular orbital approach

Tachikawa, Masanori; Kita, Yusuke; Buenker, Robert J.

doi:10.1039/c0cp01650k

Cited by 70 publications

(79 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…However, the positron can come closer to the electric dipole, since the negative end of the dipole is closer to the periphery of the molecule, and this leads to larger ǫ b . Theoretical predictions for ǫ b for positrons for this and similar molecules are now within 30% of the measurements (Tachikawa et al, 2011).…”

Section: Annihilation As a Function Of Positron Energymentioning

confidence: 49%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

233

222

View full text Add to dashboard Cite

In recent years, there has been a wealth of new science involving low-energy antimatter (i.e., positrons and antiprotons) at energies ranging from 10 2 to less than 10 −3 eV. Much of this progress has been driven by the development of new plasma-based techniques to accumulate, manipulate and deliver antiparticles for specific applications. This article focuses on the advances made in this area using positrons. However many of the resulting techniques are relevant to antiprotons as well. An overview is presented of relevant theory of single-component plasmas in electromagnetic traps. Methods are described to produce intense sources of positrons and to efficiently slow the typically energetic particles thus produced. Techniques are described to trap positrons efficiently and to cool and compress the resulting positron gases and plasmas. Finally, the procedures developed to deliver tailored pulses and beams (e.g., in intense, short bursts, or as quasi-monoenergetic continuous beams) for specific applications are reviewed. The status of development in specific application areas is also reviewed. One example is the formation of antihydrogen atoms for fundamental physics [e.g., tests of invariance under charge conjugation, parity inversion and time reversal (the CPT theorem), and studies of the interaction of gravity with antimatter]. Other applications discussed include atomic and materials physics studies and study of the electron-positron many-body system, including both classical electron-positron plasmas and the complementary quantum system in the form of Bose-condensed gases of positronium atoms. Areas of future promise are also discussed. The review concludes with a brief summary and a list of outstanding challenges.

show abstract

Section: Annihilation As a Function Of Positron Energymentioning

confidence: 49%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

233

222

View full text Add to dashboard Cite

show abstract

“…Placing HCN in the ketone family led to a predicted binding energy of 70 meV, which is a factor of two greater than the DMC result of [17]. This large value is likely an overestimate, in spite of the fact that quantum chemistry calculations tend to give lower bounds for the positron binding energies [19,20]. Experimental data for ketones shows significant deviations from linearity (see figure 5), which makes the ketone-based prediction for HCN less relaible.…”

Section: % Respectivelymentioning

confidence: 92%

“…The static-field binding energies, however, are usually quite small, and the effect of correlations (e.g., polarization of the molecule by the positron) increases the binding energy dramatically (see, e.g., [14,15,16,17,18]). Recent configuration interaction calculations for nitriles, acetaldehyde, and acetone [19,20,21] in fact give binding energies within 25-50% of the experiment, which is quite good, given the complexity of the system.…”

Section: Introductionmentioning

confidence: 91%

“…This justifies the hard-sphere model for the short-range positron repulsion. Quantum chemistry calculations of the positron density in polar molecules support the picture of a diffuse positronic cloud localized off the negatively charged end of the molecular dipole [14,17,19,20]. Note that a recent paper [22] combined a hard-sphere repulsive core with the polarization potential to model positron binding to atoms and nonpolar molecules.…”

Section: Introductionmentioning

confidence: 98%

See 1 more Smart Citation

Effect of dipole polarizability on positron binding by strongly polar molecules

Gribakin

Swann

2015

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

View full text Add to dashboard Cite

Abstract.A model for positron binding to polar molecules is considered by combining the dipole potential outside the molecule with a strongly repulsive core of a given radius. Using existing experimental data on binding energies leads to unphysically small core radii for all of the molecules studied. This suggests that electron-positron correlations neglected in the simple model play a large role in determining the binding energy. We account for these by including the polarization potential via perturbation theory and non-perturbatively. The perturbative model makes reliable predictions of binding energies for a range of polar organic molecules and hydrogen cyanide. The model also agrees with the linear dependence of the binding energies on the polarizability inferred from the experimental data [Danielson et al 2009 J. Phys. B: At. Mol. Opt. Phys. 42 235203]. The effective core radii, however, remain unphysically small for most molecules. Treating molecular polarization nonperturbatively leads to physically meaningful core radii for all of the molecules studied and enables even more accurate predictions of binding energies to be made for nearly all of the molecules considered.

show abstract

“…The zero-range potential model [23,24] captured the qualitative features for the alkanes, and there were configuration-interaction (CI) calculations for carbon-containing triatomic molecules [25,26]. For strongly polar molecules many quantum-chemistry calculations have been performed, but only a few of them allow direct comparison with experiment; recent CI calculations for nitriles, aldehydes, and acetone [27][28][29] gave binding energies within 25-50% of experimental values. A simple theoretical model was recently proposed to explain the dependence of the binding energy on the molecular dipole moment and dipole polarizability [30].…”

Section: Introductionmentioning

confidence: 99%

Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

Swann¹,

Cassidy

Deller

et al. 2016

Phys. Rev. A

View full text Add to dashboard Cite

Predicted twenty years ago, positron binding to neutral atoms has not yet been observed experimentally. A new scheme is proposed to detect positron-atom bound states by colliding Rydberg positronium (Ps) with neutral atoms. Estimates of the charge-transfer reaction cross section are obtained using the first Born approximation for a selection of neutral atom targets and a wide range of incident Ps energies and principal quantum numbers. We also estimate the corresponding Ps ionization cross section. The accuracy of the calculations is tested by comparison with earlier predictions for Ps charge transfer in collisions with hydrogen and antihydrogen. We describe an existing Rydberg Ps beam suitable for producing positron-atom bound states and estimate signal rates based on the calculated cross sections and realistic experimental parameters. We conclude that the proposed methodology is capable of producing such states and of testing theoretical predictions of their binding energies.

show abstract

Bound states of the positron with nitrile species with a configuration interaction multi-component molecular orbital approach

Cited by 70 publications

References 38 publications

Plasma and trap-based techniques for science with positrons

Plasma and trap-based techniques for science with positrons

Effect of dipole polarizability on positron binding by strongly polar molecules

Formation of positron-atom bound states in collisions between Rydberg Ps and neutral atoms

Contact Info

Product

Resources

About