Lifetimes and polarizabilities of low lying lithium S, P and D states

Ashby, R.; Wijngaarden, W. A. van

doi:10.1016/s0022-4073(02)00066-3

Cited by 7 publications

(4 citation statements)

References 35 publications

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“…For α 1 , the percentage difference between the semi-empirical model potential result of Magnier and Aubert-Frécon [48] and ours is about 7%. The values of Ashby and van Wijngaarden [49], obtained using the semi-empirical Coulomb approximation method and the values of Zhang et al [16] obtained in the framework of a frozen core Hamiltonian with a semi-empirical model potential, are very close to each other, but they differ from our results at the levels of, respectively, 0.9% and 0.8%. The experimental results of Ashby et al [50] and the relativistic calculations of Wansbeek et al [18] are expressed in the LSJ coupling scheme, which may be converted into the LS coupling by averaging over the fine structure using a (2J + 1)-weighted sum [16].…”

Section: 2 D State: Polarizabilities and Hyperpolarizabilitiessupporting

confidence: 65%

Non-relativistic ab initio calculations for $2^2S$, $2^2P$ and $3^2D$ lithium isotopes: Applications to polarizabilities and dispersion interactions

Tang,

Yan,

Shi

et al. 2009

Preprint

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The electric dipole polarizabilities and hyperpolarizabilities for the lithium isotopes 6 Li and 7 Li in the ground state 2 2 S and the excited states 2 2 P and 3 2 D, as well as the leading resonance and dispersion long-range coefficients for the Li(2 2 S)-Li(2 2 S) and Li(2 2 S)-Li(2 2 P ) systems, are calculated nonrelativistically using variational wave functions in Hylleraas basis sets. Comparisons are made with published results, where available. We find that the value of the second hyperpolarizability of the 2 2 S state is sensitive to the isotopic mass due to a near cancellation between two terms. For the 3 2 D state polarizability tensor the calculated components disagree with those measured in the sole experiment and with those calculated semi-empirically.

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Section: 2 D State: Polarizabilities and Hyperpolarizabilitiessupporting

confidence: 65%

Non-relativistic ab initio calculations for $2^2S$, $2^2P$ and $3^2D$ lithium isotopes: Applications to polarizabilities and dispersion interactions

Tang,

Yan,

Shi

et al. 2009

Preprint

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“…For the polarization of the ground state there is good agreement between our results and those from the literature. In the case of the polarizability of the first excited state, we found only one other theoretical result (Ashby & van Wijngaarden 2003), where the polarizability is calculated in the Coulomb approximation.…”

Section: R-matrix Calculationmentioning

confidence: 85%

The influence of electron collisions on non-LTE Li line formation in stellar atmospheres

Osorio

Barklem

Lind

et al. 2011

A&A

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The influence of the uncertainties in the rate coefficient data for electron-impact excitation and ionization on non-LTE Li line formation in cool stellar atmospheres is investigated. We examine the electron collision data used in previous non-LTE calculations and compare them to recent calculations that use convergent close-coupling (CCC) techniques and to our own calculations using the R-matrix with the pseudostates (RMPS) method. We find excellent agreement between rate coefficients from the CCC and RMPS calculations, and reasonable agreement between these data and the semi-empirical data used in non-LTE calculations up to now. The results of non-LTE calculations using the old and new data sets are compared and only small differences found: about 0.01 dex (∼2%) or less in the abundance corrections. We therefore conclude that the influence on non-LTE calculations of uncertainties in the electron collision data is negligible. Indeed, together with the collision data for the charge exchange process Li(3s) + H Li + + H − now available, and barring the existence of an unknown important collisional process, the collisional data in general is not a source of significant uncertainty in non-LTE Li line formation calculations.

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“…Some of these calculations are also performed using molecular codes, at the cost of atomic symmetries [25]. The one available relativistic calculation on the excited states is carried out using a rather approximate method to include the correlation effects due to the Coulomb interaction [37]. Our calculation uses a relativistic approach which considers correlation effects to all orders in the form of CC amplitudes.…”

Section: Resultsmentioning

confidence: 99%

“…These could be useful in the calculation of the dispersion coefficients of the excited states and in determining Stark shifts. So far, only a few studies have been carried out on the polarizabilities of the Li excited states [21,22,23,24,25,26]. Most of these studies use nonrelativistic theories, and we will compare those results to our relativistic calculations to assess the relevance of relativistic effects.…”

Section: Introductionmentioning

confidence: 99%

Ab initiodetermination of polarizabilities and van der Waals coefficients of Li atoms using the relativistic coupled-cluster method

et al. 2008

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We report on a technique to determine the van der Waals coefficients of lithium ͑Li͒ atoms based on relativistic coupled-cluster theory. These quantities are determined using the imaginary parts of the scalar dipole and quadrupole polarizabilities, which are evaluated using an approach that we have proposed earlier ͓B. K. Sahoo, Chem. Phys. Lett. 448, 144 ͑2007͔͒. Our procedure is fully ab initio, and avoids the sum-over-thestates approach. We present the dipole and quadrupole polarizabilities of many of the low-lying excited states of Li. Also, the off-diagonal dipole and quadrupole polarizabilites between some of the low-lying states of Li have been calculated.

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Lifetimes and polarizabilities of low lying lithium S, P and D states

Cited by 7 publications

References 35 publications

Non-relativistic ab initio calculations for $2^2S$, $2^2P$ and $3^2D$ lithium isotopes: Applications to polarizabilities and dispersion interactions

Non-relativistic ab initio calculations for $2^2S$, $2^2P$ and $3^2D$ lithium isotopes: Applications to polarizabilities and dispersion interactions

The influence of electron collisions on non-LTE Li line formation in stellar atmospheres

Ab initiodetermination of polarizabilities and van der Waals coefficients of Li atoms using the relativistic coupled-cluster method

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