ExoMol line list for HCN and HNC

The line list uses ab initio transition intensities calculated previously (Harris et al., 2002ApJ...578..657H) and extensive datasets of recently measured experimental energy levels. The resulting line list has significantly more accurate wavelengths than previous ones for these systems.

An improved value for the separation between HCN and HNC is adopted leading to an approximately 25% lower predicted thermal population of HNC as a function of temperature in the key 2000 to 3000K region. Temperature-dependent partition functions and equilibrium constant are presented. The line lists are validated by comparison with laboratory spectra and are presented in full as supplementary data to the article and at www.exomol.com.