Global modelling of the observed line positions: Dunham coefficients for the ground state of ¹⁶OH molecule

A global treatment of the available experimental data on infrared and microwave transitions of 33 vibration-rotation bands for the ground state and the data on the electronic system B²Σ⁺-X²Π of ¹⁶OH molecule was carried out. In this analysis, a global model with vibrational dependences of the parameters of the effective Hamiltonian for the diatomic molecule in the ²Π electronic state was used. As a result of the fit, a set of the ‘Dunham-type’ coefficients was obtained. They reproduce the experimental dataset of the rovibrational and pure rotational transitions as well as the data on the electronic system B²Σ⁺ - X²Π, within estimated experimental uncertainties. The determined ‘Dunham-type’ coefficients were compared with those known previously.