Medvedev, ES;
Ushakov, VG;
Conway, EK;
Upadhyay, A;
Gordon, IE;
Tennyson, J;
(2020)
Empirical normal intensity distribution for overtone vibrational spectra of triatomic molecules.
Journal of Quantitative Spectroscopy and Radiative Transfer
, 252
, Article 107084. 10.1016/j.jqsrt.2020.107084.
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Abstract
Theoretical calculations are contributing a significantly higher proportion of data to contemporary spectroscopic databases, which have traditionally relied on experimental observations and semi-empirical models. It is now a common procedure to extend calculated line lists to include ro-vibrational transitions between all bound states of the ground electronic state up to the dissociation limit. Advanced ab initio methods are utilized to calculate the potential energy and dipole moment surfaces (PESs and DMSs), and semi-empirical PESs are then obtained by combining ab initio and experimental data. The objective is to reach high accuracy in the calculated transition intensities for all parts of spectrum, i.e. to increase the predictive power of the model. We show that in order to perform this task, one needs, in addition to the standard improvements of the PES and DMS in the spectroscopically accessible regions, to extend the ab initio calculations of the PES towards the united-atom limit along the stretching coordinates. The argument is based on the correlation between the intensities of high-overtone transitions and the repulsive potential wall that has previously been theoretically established for diatomic molecules and is empirically extended here to linear and nonlinear triatomic molecules. We generate partial line lists for water and ozone, and together with an already available line list for carbon dioxide, we derive the normal intensity distribution, which is a direct consequence of this correlation. The normal distribution is not an instrument to compute highly accurate intensities, rather it is a means to analyze the intensities computed by the traditional methods.
| Type: | Article |
|---|---|
| Title: | Empirical normal intensity distribution for overtone vibrational spectra of triatomic molecules |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1016/j.jqsrt.2020.107084 |
| Publisher version: | https://doi.org/10.1016/j.jqsrt.2020.107084 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Water,Ozone,Carbon dioxide,High-overtone transitions |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10097947 |
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