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

The potential energy function of the ground X (3)Σ(g)(-) electronic state of (16)O(2) 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 υ = 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 X (3)Σ(g)(-) electronic state and the b (1)Σ(g)(+) excited electronic state.