Title: Molecular spectroscopy from first principles

Speaker: Prof. Sergei Yurchenko, University College London

Date: 2020-11-26 16:00

Location: Room B311, Zengchengkui Building

Abstract：

Theoretical spectroscopic methods are increasingly competitive with measurements and allow in many cases a more reliable determination of various molecular data, because they can be determined more accurately or are too difficult to measure reliably [1]. Over the past years there have been a rapid improvement specially in variational nuclear motion approaches to solving spectroscopic problems, which has been described as the fourth age of quantum chemistry [2]. The methodology which is commonly attributed to the spectroscopy from first principles is in fact a combination of high level ab initio (electronic structure) calculations, high level nuclear motion (variational) calculations and empirical refinement to the highly accurate experimental data (e.g. line positions) [3]. Our main of application of this methodology is the production of lists of spectroscopic transitions (line lists) for hot molecules. There is a major demand from astrophysics and elsewhere of comprehensive line lists for molecules important in the atmospheres of cool stars and extrasolar planets. These line lists provide the input for models of radiative transport through hot atmospheres and are useful for a variety of terrestrial applications. Our ExoMol project [4] has already produced more than 40 such line lists [5], which complement or even replace measured data. In this talk, I will review our recent work in the field of theoretical spectroscopy of hot molecules, discuss our methods and present some applications to different systems. I will also show examples of some key applications, which are still challenging for the modern ab initio spectroscopy.

References:

[1] J. Tennyson, J. Chem. Phys. 145, 120901 (2016).

[2] A. G. Császár, C. Fabri, T. Szidarovszky, E. Mátyus, T. Furtenbacher, and G. Czakó,  Phys. Chem. Chem. Phys. 14, 1085 (2012).

[3] J. Tennyson and S.N. Yurchenko Int. J. Quant. Chem. 117, 92, (2017).

[4] J. Tennyson and S.N. Yurchenko, Mon. Not. R. Astron. Soc. 425, 21 (2012).

[5] J. Tennyson, S. N. Yurchenko, A. F. Al-Refaie, et al., J. Mol. Spectrosc. 255, 107228 (2020).