A high accuracy computed line list for the HDO molecule

Abstract

A computed list of HD16O infrared transition frequencies and intensities is presented. The list, VTT, was produced using a discrete variable representation two‐step approach for solving the rotation–vibration nuclear motions. The VTT line list contains almost 700 million transitions and can be used to simulate spectra of mono‐deuterated water over the entire temperature range that are of importance for astrophysics. The line list can be used for deuterium‐rich environments, such as the atmosphere of Venus, and to construct a possible ‘deuterium test’ to distinguish brown dwarfs from planetary mass objects.

ExoMol molecular line lists XIX: high-accuracy computed hot line lists for H218O and H217O

“…Partridge & Schwenke (1997) constructed a fitted PES starting from a highly accurate ab initio calculation; all subsequent water potentials followed this procedure and have been based on ab initio studies of increasing sophistication. As a result there are several very good water PESs available Bubukina et al 2011 (Zobov et al 1996;Voronin et al 2010;Bubukina et al 2011), we decided to fit a Born-Oppenheimer (BO) mass-independent PES to the available data for H2 16 O and fix the adiabatic BO diagonal correction (BODC), massdependent surface to the ab initio value of Polyansky et al (2003) . We used the same fitting procedure as Bubukina et al (2011).…”

Analysis of an 18O and D enhanced water spectrum and new assignments for HD18O and D218O in the near-infrared region (6000–7000cm−1) using newly calculated variational line lists

“…For example isotopologue abundances are often used to trace atmospheric processes since isotopic variations can be caused by specific atmospheric drivers such as cometary and meteorite deposits at the top of the atmosphere. Thus, for example, the trace water isotopologue HD 18 O has been observed both in the Earth's atmosphere [4] and in the interstellar medium [5], where isotopic abundances vary significantly. In addition, data on isotopically substituted water is essential for the development of theoretical models and in particular helps to characterise effects due to the failure of the Born-Oppenheimer approximation which remains one of the major sources of uncertainty in spectroscopic calculations on water [6,7].…”

“…H 2 18 O, the second most abundant naturally occurring isotopologue of water is also well studied in this region [12,14,15,16]. Conversely the HD 18 O, D 2 18 O and HD 16 O show yet to be assigned transitions in this spectral region.…”

“…For H 2 18 O [2], HD 16 O and HD 18 O [3] an IUPAC task group (TG) has provided a comprehensive evaluation of the state of knowledge of the spectroscopy of these species. These compilations provide precise, experimentally-determined energy levels using the so-called MARVEL procedure [17] for these species where possible.…”

“…There are reliable line lists available for HD 16 O [18] and H 2 18 O [19]. For HD 18 O Tomsk [20] provide a line list avilable online based on work by Partridge and Schwenke [21,22], which has been previously employed in similar analyses of this region [23,24] contained in the IUPAC TG dataset. However this was found to be reliable at only the strongest intensities and our own HD 18 O line list was subsequently computed as part of this work.…”