ExoMol line lists – LXVI. Rotation-vibration line lists for the deuterated ammonia isotopologues 14NH2D and 14ND2H

Abstract We present new CoYuTe rovibrational line lists for the asymmetric deuterated isotopologues of ammonia, 14NH2D and 14ND2H. Variational calculations were performed using the TROVE nuclear motion program, employing newly implemented non-rigid reference frames. The semi-empirical CoYuTe potential energy surface and a high-level ab initio dipole moment surface of NH3 (CCSD(T)/aug-cc-pVQZ) were adopted. The line lists span 0–10 000 cm−1 and are applicable at temperatures up to 1000 K–1500 K. Accuracy was improved through substitution of empirically derived 14NH2D and 14ND2H MARVEL energy levels, yielding line positions consistent with available experimental data. The new line lists accurately reproduce existing infrared spectra and, for the first time, provide complete coverage of NH2D and ND2H transitions suitable for both cold astrophysical environments and high-temperature exoplanetary and brown-dwarf atmospheres. At terrestrial isotopic abundances, NH2D contributes significantly to atmospheric absorption, highlighting its importance for remote sensing and making it a strong candidate for inclusion in HITRAN. The line lists and partition functions are available from the ExoMol database at www.exomol.com.