LEVEL 8.0
Level input file, 39K-35Cl__Barton__LEVEL8.0.inp, used to produce the line list for 39K-35Cl. This input can be changed for other isotopologues and was also used for the line list of 39K-37Cl.
Dipole moment curves (DMC) were determined using high-level ab initio calculations, performed using MOLPRO (Werner et al. 2010). The final NaCl DMC was computed using an aug-cc-pCVQZ-DK basis set and the CCSD(T) method, where both core-valence and relativistic effects were also taken into account. An effective core potential ECP10MDF (MCDHF+Breit) in conjunction with the corresponding basis set (Lim et al. 2005) was used for K and aug-cc-pV(Q+d)Z was used for Cl. The electric dipole moments were obtained using the finite field method. The ab initio DMC grid points were used directly in LEVEL. The PECs were refined by fitting to the spectroscopic data. However, extending the temperature range of the spectra required consideration of highly excited levels and extrapolation of the PECs beyond the region determined by experimental input values. Multiple potential energyu forms were tested, namely the extended Morse oscillator (EMO), Morse long range (MLR) and Morse Lennard Jones potentials to achieve an optimum fit.
The original KCl ExoMol line lists of Barton et al. computed using LEVEL have been truncated by removing transitions with Δv ≥ 12. This is due to a numerical problem identified by Medvedev and co-workers with the intensities of high overtone transitions computed with LEVEL.