Is the adiabatic approximation sufficient to account for the post-Born–Oppenheimer effects on molecular electric dipole moments?

Hobson, Sandra L.; Valeev, Edward F.; Császár, Attila G.; Stanton, John F.

doi:10.1080/00268970902780262

Cited by 20 publications

(12 citation statements)

References 38 publications

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“…Also a relativistic correction, mass-velocity plus first-order Darwin term (MVD1) as produced by MOLPRO was added. Beyond Born-Oppenheimer effects have been shown to be fairly small [46] and are not considered here.…”

Section: The Hnc Fitmentioning

confidence: 99%

A new spectroscopically-determined potential energy surface and ab initio dipole moment surface for high accuracy HCN intensity calculations

Makhnev

Kyuberis

Polyansky

et al. 2018

Journal of Molecular Spectroscopy

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Calculations of transition intensities for small molecules like H 2 O, CO, CO 2 based on s high-quality potential energy surface (PES) and dipole moment surface (DMS) can nowadays reach sub-percent accuracy. An extension of this treatment to a system with more complicated internal structure -HCN/HNC (hydrogen cyanide/hydrogen isocyanide) is presented. A highly accurate spectroscopicallydetermined PES is built based on a recent ab initio PES of the HCN/HNC isomerizing system. 588 levels of HCN with J = (0, 2, 5, 9, 10) are reproduced with a standard deviation from the experimental values of σ = 0.0373 cm −1 and 101 HNC levels with J = (0, 2) are reproduced with σ = 0.37 cm −1 . The dependence of the HCN rovibrational transition intensities on the PES is tested for the wavenumbers below 7200 cm −1 . Intensities are computed using wavefunctions generated from an ab initio and our optimized PES. These intensities differ from each other by more than 1% for about 11% of the transitions tested, showing the need to use an optimized PES to obtain wavefunctions for high-accuracy predictions of transition intensities. An ab initio DMS is computed for HCN geometries lying below 11 200 cm −1 . Intensities for HCN transitions are calculated using a new fitted PES and newly calculated DMS. The resulting intensities compare 1 arXiv:1810.09314v1 [physics.chem-ph]

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Section: The Hnc Fitmentioning

confidence: 99%

A new spectroscopically-determined potential energy surface and ab initio dipole moment surface for high accuracy HCN intensity calculations

Makhnev

Kyuberis

Polyansky

et al. 2018

Journal of Molecular Spectroscopy

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“…at equilibrium and varies between zero and about 3 × 10 −3 a.u. The Born-Oppenheimer diagonal correction (also known as adiabatic correction) at equilibrium was computed by Hobson et al 30 and amounts to 8 × 10 −4 a.u. Because of its small magnitude, it was not included in the present study.…”

Section: Estimation Of the Uncertainty Of The Computed Dipolesmentioning

confidence: 99%

A global, high accuracy ab initio dipole moment surface for the electronic ground state of the water molecule

Lodi¹,

Tennyson²,

Polyansky³

2011

The Journal of Chemical Physics

165

139

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A highly accurate, global dipole moment surface (DMS) is calculated for the water molecule using ab initio quantum chemistry methods. The new surface is named LTP2011 and is based on all-electron, internally contracted multireference configuration interaction, including size-extensivity corrections in the aug-cc-pCV6Z basis set. Dipoles are computed as energy derivatives and small corrections due to relativistic effects included. The LTP2011 DMS uses an appropriate functional form that guarantees qualitatively correct behaviour even for most high energies configuration (up to about 60,000 cm(-1)), including, in particular, along the water dissociation channel. Comparisons with high precision experimental data show agreement within 1% for medium-strength lines. The new DMS and all the ab initio data are made available in the supplementary material.

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“…where X=H, D, etc..) makes these species rigorously nonpolar, a small permanent electric dipole moment exists in the corresponding heteroisotopic isotopologues (like HD), thereby making vibrational dipolar transitions of these molecules weakly allowed. While it is perhaps traditional to associate this weak electrical charge asymmetry (the density of charge located on the deuteron differs slightly from that located on the proton) with "nonadiabatic effects" that mix different (clamped-nucleus) adiabatic wave functions [23][24][25][26][27][28][29][30], recent works, like those based on the so called Post-BO approach [7,[31][32][33], on the so-called non-BO variational approach [34,35], or on the approximate adiabatic variational approach [36] have convincingly demonstrated that the overwhelming majority of this effect resides in the so-called adiabatic (diagonal Born-Oppenheimer) correction. Hence within this perspective, the intensity of fundamental and overtone vibrational transitions in molecules like HD can be calculated by the usual methods as currently done for the calculation of the hyperfine couplings.…”

mentioning

confidence: 99%

Hyperfine transitions in the first overtone mode of hydrogen deuteride

Dupré

2020

Phys. Rev. A

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Beyond the metrology and computational challenges associated with molecular hydrogen, key data are expected to assess the physics of simple molecular systems, and even the New Physics beyond the Standard Model. To assist the deciphering of Doppler-free spectra obtained at very high accuracy (∼ 10 −9), we report on hyperfine transitions of HD in the lowest vibrational levels of the ground electronic state. Using the spin-rotation, nuclear spin-spin and quadrupolar hyperfine couplings determined by means of high-level quantum-chemical calculations, the hyperfine energy levels, and the associated line intensity have been obtained by using tensorial momentum algebra. To illustrate our purpose, the hyperfine line intensity of two specific transitions (P 1 and R 1) belonging to the first overtone of HD is reported and commented on. The calculated stick spectra emphasize the experimental challenge (in terms of sensitivity and of spectral resolution) associated with the spectral analysis, because the lines can be apart by less than 10 kHz.

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Is the adiabatic approximation sufficient to account for the post-Born–Oppenheimer effects on molecular electric dipole moments?

Cited by 20 publications

References 38 publications

A new spectroscopically-determined potential energy surface and ab initio dipole moment surface for high accuracy HCN intensity calculations

A new spectroscopically-determined potential energy surface and ab initio dipole moment surface for high accuracy HCN intensity calculations

A global, high accuracy ab initio dipole moment surface for the electronic ground state of the water molecule

Hyperfine transitions in the first overtone mode of hydrogen deuteride

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