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Goebel, Dirk; Hohm, Uwe

doi:10.1103/physreva.52.3691

Cited by 66 publications

(55 citation statements)

References 23 publications

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“…The present calculation gives 50.03 a.u., while one experiment gave 49.6 ± 1.6 a.u. [18]. However, another measurement by the same group gave 45.3 ± 0.2 a.u.…”

Section: Structure and Properties Of Neutral Cadmiummentioning

confidence: 90%

“…[22]. The experimental results for the energies, oscillator strengths, and polarizabilities are taken from various sources [18,19,[29][30][31] and, where available, their uncertainties in the last digits are given in parentheses. The e + Cd CI wave function consists of a linear combination of three-particle states which are antisymmetric in the interchange of the two electrons,…”

Section: Structure and Properties Of Neutral Cadmiummentioning

confidence: 99%

“…The cadmium atom is a good candidate to support a 2 P o shape resonance since it has a dipole polarizability between 44 and 50 a.u. [15,[18][19][20] and is also known to bind a positron [21,22].The present paper reports on improved CI calculations of the e + Cd bound state and the e + -Cd elastic scattering and annihilation cross sections. The orbital basis sets are larger, and thus estimates of the elastic and annihilation cross sections are better than previous work [22].…”

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Elastic positron-cadmium scattering at low energies

Bromley

Mitroy

2010

Phys. Rev. A

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The elastic and annihilation cross sections for positron-cadmium scattering are reported up to the positroniumformation threshold (at 2.2 eV). The low-energy phase shifts for the elastic scattering of positrons from cadmium were derived from the bound and pseudostate energies of a very large basis configuration-interaction calculation of the e + -Cd system. The s-wave binding energy is estimated to be 126 ± 42 meV, with a scattering length of A scat = (14.2 ± 2.1)a 0 , while the threshold annihilation parameter, Z eff , was 93.9 ± 26.5. The p-wave phase shift exhibits a weak shape resonance that results in a peak Z eff of 91 ± 17 at a collision energy of about 490 ± 50 meV. Calculations over the past decade have demonstrated that positrons can form bound states with a wide range of neutral atoms [1,2]. Apart from the intrinsic interest in the quantum mechanics of these systems, the strong evidence for positron binding to atoms has provided support for the hypothesis that positron-molecule bound states associated with vibrationally excited states are predominantly responsible for the massive positron annihilation rates observed in many molecular-gas experiments [3]. The experimental realization and identification of positronic atoms and molecules is very difficult, so evidence for their existence is best sought indirectly by means of scattering experiments.The first-principles calculation of positron-atom interactions is a challenging proposition due to the tendency for the atomic electrons to localize around the positron, forming a composite structure somewhat akin to the positronium (Ps) atom [1,4]. The configuration-interaction (CI) method has been used to determine the energies of the positronic magnesium (e + Mg) and positronic zinc (e + Zn) ground states. In addition, their low-energy elastic and annihilation cross sections have been extracted from the energies of physical and low-energy pseudostates [5,6]. The presence of a Ps-like cluster dramatically slows down the convergence of the CI expansion with respect to the partial waves included in the orbital basis [1,4]. For example, the prediction of the 2 P o excited state of e + Ca was performed with a CI basis of dimension 900 000 [7,8]. Even then, the prediction of binding was reliant on an extrapolation to the → ∞ limit.The structures that are present in electron-atom scattering experiments [10]. Other calculations on the positron-copper and positron-zinc systems (which both support a 2 S e bound state) revealed a structure in their low-energy annihilation spectrum due to a weak resonance in their 2 P o scattering channels [6,11].The reason for the strong structure in the e + -Mg system, and the weaker structures in the e + -Cu and e + -Zn systems, is the attractive polarization interaction between the atom and the positron. The magnesium atom has a dipole polarizability, α d , of 71.35 a.u. [12][13][14][15] (an atomic unit corresponds to one a 3 0 ), while that of copper is 41.7 ± 3.4 a.u. [16] (there are other estimates that lie toward the upper side ...

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“…The present calculation gives 50.03 a.u., while one experiment gave 49.6 ± 1.6 a.u. [18]. However, another measurement by the same group gave 45.3 ± 0.2 a.u.…”

Section: Structure and Properties Of Neutral Cadmiummentioning

confidence: 90%

Section: Structure and Properties Of Neutral Cadmiummentioning

confidence: 99%

mentioning

confidence: 94%

mentioning

confidence: 99%

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Elastic positron-cadmium scattering at low energies

Bromley

Mitroy

2010

Phys. Rev. A

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“…According to this simple relation, the effect of black-body radiation photons on Ä L is small in the case of reactions with helium (approximately 1% at 10000K), but it may become important in the case of reactions with heavier elements and open shell systems, which tend to have much larger oscillator strengths sum ratios a\ Q = S(-4)/S( -2) (e.g. Li:«| Q = 214au [11], Cd:a,] Q = 18.9 au [24]). …”

Section: (T) Ii(uj T)mentioning

confidence: 99%

The Influence Of Matter And Black-Body Radiation Photons On The Dipole Polarizabilities A And γ Of Atoms

Hohm

1996

Zeitschrift Für Naturforschung A

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The influence of the surroundings on the linear dipole polarizability a and second hyperpolarizability 7 is discussed in terms of the density om of isotropically distributed matter as well as the density qp of thermal black-body radiation photons, a and 7 of the rare gas atoms are studied as examples. At standard conditions, both effects are of comparable size for the rare gases. Possible consequences for ion-molecule reaction rate constants in astronomical environments are suggested.Apart from a few exceptions theoretical calculations of molecular properties ^ pertain to single, noninteracting particles (see e.g. [1]). In experiments, however, the properties of single particles are more or less influenced by interaction with the surrounding matter and black-body radiation photons [2 -6], This is the case even for gases at ambient temperature and pressure.Concerning the dipole polarizabilities a and 7, the first effect is well-known. Perturbation of a and 7 by electric fields produced by the surrounding isotropically distributed matter is usually formulated in a virial expansion of these properties in powers of the molar density £>m = (N/V)m/N A of the matter,In the case of the static linear dipole polarizability

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Static and Frequency‐Dependent Dipole–Dipole Polarizabilities of All Closed‐Shell Atoms up to Radium: A Four‐Component Relativistic DFT Study

et al. 2008

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We test the performance of four-component relativistic density functional theory by calculating the static and frequency-dependent electric dipole-dipole polarizabilities of all (ground-state) closed-shell atoms up to Ra. We consider 12 nonrelativistic functionals, including three asymptotically shape-corrected functionals, by using two smooth interpolation schemes introduced by the Baerends group: the gradient-regulated asymptotic connection (GRAC) procedure and the statistical averaging of (model) orbital potentials (SAOP). Basis sets of doubly augmented triple-zeta quality are used. The results are compared to experimental data or to accurate ab initio results. The reference static electric dipole polarizability of palladium has been obtained by finite-field calculations using the coupled-cluster singles, doubles, and perturbative triples method within this work. The best overall performance is obtained using hybrid functionals and their GRAC shape-corrected versions. The performance of SAOP is among the best for nonhybrid functionals for Group 18 atoms but its precision degrades when considering the full set of atoms. In general, we find that conclusions based on results obtained for the rare-gas atoms are not necessarily representative of the complete set of atoms. GRAC cannot be used with effective core potentials since the asymptotic correction is switched on in the core region.

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Dispersion of the refractive index of cadmium vapor and the dipole polarizability of the atomic cadmium1S

Cited by 66 publications

References 23 publications

Elastic positron-cadmium scattering at low energies

Elastic positron-cadmium scattering at low energies

The Influence Of Matter And Black-Body Radiation Photons On The Dipole Polarizabilities A And γ Of Atoms

Static and Frequency‐Dependent Dipole–Dipole Polarizabilities of All Closed‐Shell Atoms up to Radium: A Four‐Component Relativistic DFT Study

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