Ab initiocalculations of14N and15N hyperfine structures (original) (raw)
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Ab Initio Calculation of Hyperfine Interaction Parameters: Recent Evolutions, Recent Examples
Hyperfine Interactions, 2004
For some years already, ab initio calculations based on Density Functional Theory (DFT) belong to the toolbox of the field of hyperfine interaction studies. In this paper, the standard ab initio approach is schematically sketched. New features, methods and possibilities that broke through during the past few years are listed, and their relation to the standard approach is explained. All this is illustrated by some highlights of recent ab initio work done by the Nuclear Condensed Matter Group at the K.U.Leuven.
Physica Scripta, 1992
We have calculated relativistic energies, weighted oscillator strengths and transition probabilities for electric dipole (E1) transitions among the terms belonging to 1snl (np9, lp3) configurations in helium-like sulphur. The calculations are based upon the multiconfiguration Hartree-Fock method within the framework of Breit-Pauli relativistic corrections. Our calculated values are also compared with other experimental and theoretical results. r the wavelengths and relative intensities of the intercombination lines 3 3 P 1 -1 1 S 0 in the spectra of laserproduced plasma. Lin et al. calculated oscillator strengths for the transitions m 3,1 S 0,1 -n 3,1 P 1 (3pm, np5). Mewe and Schrijver [16] evaluated line intensities of all lines for helium-like ions. Drake presented frequencies and transition rates in some helium-like ions. Berry et al. analyzed wavelengths and fine structure of 2s-2p transition in two-electron ions and compared them with theory and experiments. The wavelengths of 2 3 S-2 3 P transitions in S XV were measured by Livingston et al. . Precision wavelength measurements for 2 3 S 1 -2 3 P 0,2 transitions and 2 1 P 1 -1 1 S 0 and 2 3 P 1 -1 1 S 0 transition in helium-like sulphur were presented by DeSerio et al. [20] and Schleinkofer et al. . Energy levels for 1snl (n ¼ 2-5) states were calculated the perturbation method by power series in 1/Z and aZ by Vainshtein and Safronova . A theoretical study of two-photon emission rates for the 2 1 S state and n ¼ 1 and 2 states were presented by Drake . A comparison between calculated and measured wavelengths of resonance transitions were reported by Aglitsky et al. . The energies of the n ¼ 2 triplet states in helium-like ions were calculated with relativistic many-body perturbation theory by Johnson and Sapirstein [26]. Berry et al. [27] made a careful comparison of the triplet state energies. The results for relativistic configuration-interaction calculations of n ¼ 2 triplet states of helium-like ions were presented by Chen et al. [28]. Relativistic many-body calculations of n ¼ 1 and 2 states were observed by Plante et al. [29]. The list of wavelengths, oscillator strengths and statistical weights for spectral lines arising from the ground state were presented by Verner et al. [30]. Howie et al. [31] measured the wavelengths using photographic spectroscopy of beam foil n ¼ 2 triplet states. Kato et al. [32] reported theoretical atomic data of satellite spectra for helium-like sulphur with different methods. Two-photon decay rates of metastable 2 1 S 0 and 2 3 S 1 states were presented for helium-like ions in the Z ¼ 2-100 range by Derevianko and Johnson [33]. Safronova and Johnson [34] studied energy levels and autoionizing rates of some levels for helium-like with Z ¼ 4-54 ions. Kimura et al. [35] calculated rate coefficients for electron impulse excitation of helium-like ions with the Dirac R-matrix approach. Kingston et al. [36] obtained spontaneous transition rates for E1, M1, E2 and M2 transitions using fully relativistic GRASP and CIV3 codes.
Hyperfine Structure of1snpP3Terms ofLi6,7ii
Physical Review A, 1973
COLLISION-INDUCED ABSORPTION IN ALKALI-METAL-ATOM-.. . 1609 300'K were calculated in the quantum-mechanical formulation. To compare the two methods of calculation, we have evaluated the classical-path expressio~for NaHe it 300'K at several frequencies. The results are included in Fig. 1. The classical approximation is very accurate at low frequencies, but at high frequencies it overestimates the absorption. At high frequencies the classical turning points 8& and 8& in the initial and final states are considerably different and in the quantum-mechanicaltreatment the region 8; &8 &R& contributes little to the matrix elements of D (R). The dependence of the absorption coefficient on the interaction potential is similar to that of the elastic scattering cross section, but the thermal averaging tends to suppress detailed information of the kind that can be obtained from cross-section measurements.
Laboratory Measurements of the Hyperfine Structure of H 14 N 12 C and D 14 N 12 C
The Astrophysical Journal, 2006
The nuclear quadrupole hyperfine structure of H 14 N 12 C and D 14 N 12 C has been resolved in the laboratory for the first time using millimeter-wave absorption spectroscopy. The transient species were produced in a pulsed DC discharge nozzle, and Doppler broadening effects were minimized by propagating the millimeter waves coaxially with the supersonic molecular beam. New rest frequencies for the , , and J p 1-0 J p 2-1 J p 3-2 rotational transitions of the ground vibrational state were determined. The nuclear quadrupole coupling constants derived from the spectra are kHz for H 14 N 12 C and kHz and (eQq) p 264.5 ע 4.6 (eQq) p 294.7 ע 13.
Re-examination of the hyperfine structure of 14NH2
The Journal of Chemical Physics, 1995
The hyperfine structure of the 14 NH 2 radical is investigated by means of multireference single and double configuration interaction ͑MRCI͒ techniques. Particular attention is paid to the dependence of the coupling constants on the basis set, reference space, and configuration selection energy threshold. It is found that convergence can be obtained only if more than 83 reference configurations are included with an energy threshold of at least 10 Ϫ7 hartree. With up to 126 reference configurations, an energy threshold smaller than 10 Ϫ8 hartree and an uncontracted ͑13s8p2d/8s2p͒ basis set, the MRCI isotropic couplings ͑27.44 and Ϫ68.47 MHz for N and H, respectively͒ are in very good agreement with experimental data ͑27.9 and Ϫ67.2 MHz, respectively͒.
The hyperfine coupling constants of19F?2: An ab initioMRD-CI basis set study
International Journal of Quantum Chemistry, 1989
The isotropic (aiso) and dipolar (Adip) hyperfine coupling constants of 19 F2 were obtained from MRD-CI wave functions using a variety of basis sets. In series I, increasing numbers of d functions were added to a 5s4p contracted Huzinaga!Dunning basis. In series II, the 5s3p basis set was uncontracted in several steps until 9s5p was reached, to which were added from one to three d-polarization functions. Cl parameters (selectioo threshoids and the number of reference coofiguratioos) were also varied. A study of the R dependence of aiso and Adip was perfonned. The best values obtained at Re are 260 G for aiso aod 308 G for Adip• compared with experimental values of about 280 G for a; 10 and 320 G for Adip•
Hyperfine structure measurements of antiprotonic ³He using microwave spectroscopy
2012
the two measured transition frequencies are ν −− HF = 11.12548(08) GHz and ν −+ HF = 11.15793(13) GHz. Zusammenfassung Zielsetzung dieses Projekts war die Messung der Hyperfeinstruktur von p 3 He + mittels Laser-Mikrowellen-Laser Spektroskopie. Antiprotonisches Helium (pHe +) ist ein neutrales, exotisches Atom, bestehend aus einem Heliumkern, einem Elektron und einem Antiproton. Die Wechselwirkungen der einzelnen Drehmomente erzeugen eine Hyperfeinaufspaltung (HFS) innerhalb der Energiezustände. Die 3% der gebildeten Atome antiprotonischen Heliums, die in einem metastabilen, durch Strahlung zerfallenden Zustand verbleiben, haben eine Lebensdauer von 1-3 µs. Das dadurch definierte Zeitfenster wird genützt, um mikrowellen-spektroskopische Messungen durchzuführen. Die Hyperfeinstruktur von p 4 He + wurde bereits vollständig untersucht. Mit diesen Messungen kann man das magnetische Moment des Antiprotons bestimmen. Der Vergleich des magnetischen Moments für Proton und Antiproton gibt Aufschlussüber eine mögliche CPT-Verletzung. Die komplexere Struktur von p 3 He + ermöglicht eine Gegenprüfung der Ergebnisse mit p 4 He + sowie einen restriktiveren Test der theoretischen Berechnungen und Methoden. Das Prinzip der Messung basiert darauf eine Laserinduzierte Asymmetrie zwischen den der HF Zustände zu erzeugen. Danach wird mit Hilfe von Mikrowellenstrahlung ein Besetzungsübergang zwischen diesen Zuständen stimuliert und darauffolgend ein weiterer gesendet, um die erfolgte Besetzungsänderung zu messen. Für die wurden mehrere kryogenische Kavitäten simuliert, gebaut und getestet. Ein wesentlicher Teil meiner Arbeit bestand darin Berechnungen und finite-element Simulationen dazu durchzuführen ebenso wie umfangreiche Tests, Diagnostik und Kalibrierung dieser Hochfrequenzstrukturen und des gesamten Mikrowellen-Aufbaus. Der Fokus meines Projekts war die Umsetzung der spektroskopischen Messungen am CERN (ebenso wie die Organisation oder auch die Betreuung von Projektstudenten) und die anschliessende Datenanalyse sowie numerische Simulationen derÜbergänge zwischen den Hyperfeinzuständen. Zwei der vi Zusammenfassung vier messbaren Linien des (n, L) = (36, 34) Zustands in p 3 He + konnten zum ersten Mal beobachtet werden und stimmen gut mit den QED Berechnungenüberein. Die gemessenen Werte für diese beidenÜbergangsfrequenzen sind ν −− HF = 11.12548(08) GHz und ν −+ HF = 11.15793(13) GHz.
The Journal of Chemical Physics, 1992
The hyperfine coupling constants (hfcc) Aiso and Aij are calculated for the atoms of NH2 in its two lowest-lying electronic states at various molecular geometries by means of the ab initio multireference configuration interaction method. The vibronically averaged values of the hfccs for the K=0 and 1 levels in 14N 1H2 in the energy range up to 20 000 cm−1 are computed. Polarization effects which determine Aiso as well as a simple model to describe the dipolar hfccs are discussed. All results are in excellent agreement with experimental data.
Relativistic effects on the hyperfine structures of2p4(3P)3p2Do,4Do, and4Poin19F i
Physical Review A, 2013
The hyperfine interaction constants of the 2p 4 (3 P)3p 2 D o 3/2,5/2 , 4 D o 1/2−7/2 and 4 P o 1/2−5/2 levels in neutral fluorine are investigated theoretically. Large-scale calculations are carried out using the multiconfiguration Hartree-Fock (MCHF) and Dirac-Hartree-Fock (MCDHF) methods. In the framework of the MCHF approach, the relativistic effects are taken into account in the Breit-Pauli approximation using non relativistic orbitals. In the fully relativistic approach, the orbitals are optimized using the Dirac-Coulomb Hamiltonian with correlation models inspired by the non relativistic calculations. Higher-order excitations are captured through multireference configuration interaction calculations including the Breit interaction. In a third (intermediate) approach, the Dirac-Coulomb-Breit Hamiltonian matrix is diagonalized in a relativistic configuration space built with non relativistic MCHF radial functions converted into Dirac spinors using the Pauli approximation. The magnetic dipole hyperfine structure constants calculated with the three relativistic models are consistent and reveal unexpectedly large effects of relativity for 2 D o 5/2 , 4 P o 3/2 and 4 P o 5/2. The agreement with the few available experimental values is satisfactory. The strong J-dependence of relativistic corrections on the hyperfine constants is investigated through the detailed analysis of the orbital, spin-dipole and contact relative contributions calculated with the non relativistic magnetic dipole operator.
Physical Review A, 2000
Isotope shifts and hyperfine structures have been determined for the three near-ultraviolet transitions 405.8 nm (6s 2 6p 2 3 P 2 -6s 2 6p7s 3 P 1 o ), 368.3 nm (6s 2 6p 2 3 P 1 -6s 2 6p7s 3 P 0 o ), and 364.0 nm (6s 2 6p 2 3 P 1 -6s 2 6p7s 3 P 1 o ) in stable isotopes of Pb I using the technique of saturated absorption spectroscopy in a sputtered vapor. The isotope shifts for these transitions and the magnetic hyperfine interaction constants for the 6s 2 6p 2 3 P 1,2 metastable levels are the first Doppler-free determinations for these systems reported in the literature to our knowledge. Combined with experimental data, previously given in the literature, and pseudorelativistic Hartree-Fock estimates, the field shifts ͑FS's͒ of seven relevant configurations are deduced: FS(6s 2 6p7s)ϭ2461 MHz, FS(6s 2 6p9p)ϭ1838 MHz, FS(6s 2 6p6d)ϭ1820 MHz, FS(6s 2 6p7d) ϭ1668 MHz, FS(6s 2 6p8s)ϭ2132 MHz, FS(6s 2 6p7p)ϭ395 MHz, and FS(6s 2 6p5 f )ϭϪ461 MHz, referred to 6s 2 6p 2 . The hyperfine-structure integrals deduced from the experimental A factors for p electrons of the ground configuration 6s 2 6p 2 are in good agreement with results of ab initio calculations.