Present State of the Calculation of Radiative Lifetimes of Molecules

Oddershede, Jens

doi:10.1088/0031-8949/20/5-6/005

Cited by 27 publications

(8 citation statements)

References 62 publications

(57 reference statements)

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“…25 However, the conversion of lifetime measurements to "electronic OSCillator strengths" rests on the assumptions that the branching ratios from the B and C states to the A in state is known and that the electronic tranSition moments vary slowly with internuclear separation. 32 The first assumption is the most crucial one and a change in the estimates of the branching ratios may give a sizeable change in the "experimental" oscillator strengths, thus leading to experimental results in and experimental estimates of the equilibrium electronic oscillator strengths did not agree nearly as well. This difference is caused by the variation in electronic transition moment with the internuclear separation.…”

Section: Numerical Applicationsmentioning

confidence: 99%

See 1 more Smart Citation

Transition moments and dynamic polarizabilities in a second order polarization propagator approach

Nielsen

Jørgensen

Oddershede³

1980

The Journal of Chemical Physics

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396

123

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We have formulated a polarization propagator approach which yields excitation energies, transition moments, and dynamic polarizabilities which are consistent through second order in the electronic repulsion. Certain terms are proven to be missing in our previous second order calculations of transition moments and dynamic polarizabilities and in the equation-of-motion calculations of the same quantities. Numerical calculations on carbon monoxide are performed. The calculations show that the major difference between the polarizability (and some transition moments) in the RPA and in the second order polarization propagator approximation is due to these terms. The total effect of all correction terms has been to improve considerably the agreement between theoretical and experimental estimates of the excitation properties for carbon monoxide.

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Section: Numerical Applicationsmentioning

confidence: 99%

“…This difference is caused by the variation in electronic transition moment with the internuclear separation. 32 The calculation of the dipole polarizability is strongly affected by the" density -shift" terms and the second order term in the metric matrix. The least important term in the (positive) extra 2p -2h term, W~ [see Eq.…”

Section: Numerical Applicationsmentioning

confidence: 99%

Transition moments and dynamic polarizabilities in a second order polarization propagator approach

Nielsen

Jørgensen

Oddershede³

1980

The Journal of Chemical Physics

Self Cite

396

123

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“…All the dipole matrix element occurring in equation (13) are non zero for the µ x and µ y components of the dipole operator, and the extension of equations (11) and (13) to the case of more than one singlet or/and triplet Π state is straightforward.…”

Section: B Spin-orbit Couplingmentioning

confidence: 99%

Radiative lifetime of the a Σ3+ state of HeH+ from ab initio calculations

Loreau

Liévin

Vaeck

2010

The Journal of Chemical Physics

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The first metastable triplet state of HeH(+) was found to be present in ion beam experiments, with its lifetime estimated to be between hundreds of milliseconds and thousand of seconds. In this work, we use ab initio methods to evaluate the radiative lifetimes of the six vibrational levels of the a (3)Σ(+) of HeH(+). The transition a (3)Σ(+)→X (1)Σ(+) is spin-forbidden, but acquires intensity through spin-orbit interaction with the singlet and triplet Π states. Large scale CASSCF/MRCI calculations using an adapted basis set were performed to determine the potential energy curves of the relevant states of HeH(+) as well as the matrix elements of the dipole and spin-orbit operators. The wave functions and energies of the vibrational levels of the a (3)Σ(+) and X (1)Σ(+) states are obtained using a B-spline method and compared to previous works. We find that the radiative lifetime of the vibrational levels increases strongly with v, the lifetime of the v=0 state being 150 s. We also analyze the contributions from discrete and continuum parts of the spectrum. With such a long lifetime, the a (3)Σ(+) state could have astrophysical implications.

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“…(2) taking into account only the electronic contribution, computed at a fixed nuclear configuration, namely, that corresponding to the equilibrium geometry of the excited emitting state jai (U-F bond distance: 2.147 Å ), using the electronic spin-orbit wavefunctions of states ja g a i and jb g b i and the m 2 ab values obtained are, therefore, an approximation to more accurate values that would include the effects of vibrations [13].…”

Section: Methods and Details Of The Calculationsmentioning

confidence: 99%

“…If the values of DE ab are expressed in cm À1 and those of m ab in au, this expression, for A ab in ns À1 , becomes: [13]). In turn, the lifetime for spontaneous emission from state ja g a i, t, has been calculated as [13,14] t…”

Section: Methods and Details Of The Calculationsmentioning

confidence: 99%