LEVEL 8.0
The Level input file 31P-14N__YYLT__level.inp was used to produce the line list for 31P-14N. This is the Level input for the parent isotopologue but can be altered for others.
Line lists are produced using an empirical potential energy curve that was obtained by fitting to the experimental transition frequencies available in the literature, in conjunction with an accurate, high level ab initio dipole moment curve. In these calculations the programs DPotFit and LEVEL 8.0 were used.
This model reproduces the experimental wavenumbers with a root-mean-square error of 0.004 cm-1. The highest level of ab initio theory considered was used in this work, MRCI+Q / aug-cc-pCV6Z, to compute a new DMC. Dipoles were computed as the derivative of the MRCI+Q energy with respect to an external electric field along the internuclear axis for vanishing field strength (Lodi & Tennyson 2010); field strengths ±5 × 10-4 a.u. were used and dipoles on a grid r = 2.1 to 6.1 a0 in steps of 0.05 a0 were computed.
The original PN ExoMol line lists of Yorke et al. computed using LEVEL have been truncated by removing transitions with Δv ≥ 6. This is due to a numerical problem identified by Medvedev and co-workers with the intensities of high overtone transitions computed with LEVEL.