Code used:

DUO, v. 211 (CCPForge)

Input:

Duo inputs for isotopologue 31P-16O.

31P-16O__POPS_Duo_curves.inp (contains curves as grid points)
31P-16O__POPS_Duo.inp (contains parameters)

The input files contain experimental line positions and energy terms values used to build the model.  The PE, DM, SO and EAM functions are represented by expansion parameters as well as on grids of points. The Duo code can be accessed via http://www.exomol.com/software/.

Zero point energy (ZPE): 

503.13 cm-1 relative to J=0.5, v=0, e