# ExoMol line list XXXIV: A Rovibrational Line List for Phosphinidene (PH) in its $X\,{}^3\Sigma^-$ and $a\,{}^1\Delta$ Electronic States

## TL;DR

This paper presents a comprehensive rovibrational line list for phosphinidene (PH) in its ground and excited states, combining empirical and ab initio data to aid atmospheric studies of exoplanets and cool stars.

## Contribution

The creation of an extensive, accurate line list for PH using a hybrid approach of empirical fitting and ab initio calculations, covering a wide temperature range.

## Key findings

- Line list contains 65,055 transitions for 2,528 states.
- Root mean square error of 0.01 cm$^{-1}$ in transition frequencies.
- Line list is publicly available for spectral modeling.

## Abstract

A rovibronic line list for the ground ($X$ $^3\Sigma^-$) and first excited ($a$ $^1\Delta$) states of phosphinidene, $^{31}$PH, is computed. The line list is designed for studies of exoplanetary and cool stellar atmospheres with temperatures up to 4000 K. A combination of empirical and ab initio data are used to produce the line list: potential energy curves (PECs) are fitted using experimental transition frequencies; these transitions are reproduced with a root mean square error of 0.01 cm$^{-1}$. The nuclear Schr\"{o}dinger is solved using these PECs plus Born-Oppenheimer and spin splitting correction terms. Line intensities and Einstein $A$ coefficients are computed using ab initio Dipole Moment Curves (DMC) $X$-$X$ and $a$-$a$. The resulting LaTY line list, which contains 65055 transitions for 2528 rovibronic states up to 24500 cm$^{-1}$ and $J=80$ is used to simulate spectra in emission and absorption at a range of temperatures. The line list is made available in electronic form at the CDS and ExoMol databases.