The potential energy function of the ground electronic state of ¹⁶O₂

The potential energy function of the ground X³ Σ_g ^- electronic state of ¹⁶O₂ has been obtained in analytical form by employing a fully quantum-mechanical direct potential fitting method. Term values generated from highly precise Dunham coefficients were employed in the direct fit, yielding a potential energy function that is accurate up to ν = 31, or up to an energy that is 90% of the dissociation limit. The term values are represented with a standard deviation of 0.0031 cm^-1 by the quantum-mechanical eigenvalues of the derived potential energy function. There is considerable evidence for N-dependent nonadiabatic coupling between the ground X³ Σ_g ^- electronic state and the b¹ Σ_g ⁺ excited electronic state.