# Room temperature line lists for CO\2 symmetric isotopologues with \textit{ab initio} computed intensities

## TL;DR

This paper presents high-accuracy, room temperature line lists for six symmetric isotopologues of CO2, computed using ab initio methods, to support remote sensing with sub-percent intensity accuracy.

## Contribution

The authors developed and validated new ab initio computed line lists for CO2 isotopologues, achieving sub-percent accuracy for strong band intensities, suitable for remote sensing applications.

## Key findings

- Most line intensities for strong bands are predicted with sub-percent accuracy.
- Line lists are validated against recent measurements and HITRAN2012 database.
- Reliable line positions are generated using an effective Hamiltonian.

## Abstract

Remote sensing experiments require high-accuracy, preferably sub-percent, line intensities and in response to this need we present computed room temperature line lists for six symmetric isotopologues of carbon dioxide: $^{13}$C$^{16}$O$_2$, $^{14}$C$^{16}$O$_2$, $^{12}$C$^{17}$O$_2$, $^{12}$C$^{18}$O$_2$, $^{13}$C$^{17}$O$_2$ and $^{13}$C$^{18}$O$_2$, covering the range 0-8000 \cm. Our calculation scheme is based on variational nuclear motion calculations and on a reliability analysis of the generated line intensities. Rotation-vibration wavefunctions and energy levels are computed using the DVR3D software suite and a high quality semi-empirical potential energy surface (PES), followed by computation of intensities using an \abinitio\ dipole moment surface (DMS). Four line lists are computed for each isotopologue to quantify sensitivity to minor distortions of the PES/DMS. Reliable lines are benchmarked against recent state-of-the-art measurements and against the HITRAN2012 database, supporting the claim that the majority of line intensities for strong bands are predicted with sub-percent accuracy. Accurate line positions are generated using an effective Hamiltonian. We recommend the use of these line lists for future remote sensing studies and their inclusion in databases.