The rovibrational spectrum of BeH, MgH and CaH at high temperatures in the $X\,{}^2\Sigma^+$ state: a theoretical study

TL;DR

This paper provides comprehensive, high-temperature rovibrational line lists for BeH, MgH, and CaH molecules using a combination of empirical and ab initio methods, crucial for modeling exoplanetary atmospheres.

Contribution

It introduces new, accurate line lists for BeH, MgH, and CaH in their ground states, suitable for temperatures up to 2000K, combining empirical data and ab initio calculations.

Findings

Line lists cover temperatures up to 2000K.

Accurate rovibrational energy levels and line intensities provided.

Line lists are publicly available online.

Abstract

Accurate line lists for three molecules, BeH, MgH and CaH, in their ground electronic states are presented. These line lists are suitable for temperatures relevant to exoplanetary atmospheres and cool stars (up to 2000K). A combination of empirical and \textit{ab initio} methods is used. The rovibrational energy levels of BeH, MgH and CaH are computed using the programs Level and DPotFit in conjunction with `spectroscopic' potential energy curves (PECs). The PEC of BeH is taken from the literature, while the PECs of CaH and MgH are generated by fitting to the experimental transition energy levels. Both spin-rotation interactions (except for BeH, for which it is negligible) and non-adiabatic corrections are explicitly taken into account. Accurate line intensities are generated using newly computed \textit{ab initio} dipole moment curves for each molecule using high levels of theory. Full line lists of rotation-vibration transitions for $^9$BeH, $^{24}$MgH, $^{25}$MgH, $^{26}$MgH and $^{40}$CaH are made available in an electronic form as supplementary data to this article and at \url{www.exomol.com}.