A potential function for HNO ùA″ derived using a vibronic (Renner-Teller) variational calculation

Abstract

An analytic potential function for the à ¹ A″ state of HNO/DNO has been constructed using spectroscopic term values, thermochemical data, and the results of ab initio calculations. The potential function is of the two-valued model introduced by Carter and Murrell, and corresponds to the lower eigenvalue of a 2 × 2 matrix with components that transform as ¹∏ and ¹Δ for linear geometries. The vibronic hamiltonian takes into account the nonadiabatic energy arising from the Renner-Teller effect. Its eigenvalues have been obtained variationally using a large basis set, and fitted to experimental data with a mean error of 16 cm^-1 over a 5000 cm^-1 energy range. A critical discussion of this potential function underlines the desirability of further ab initio calculations, particularly for linear and near-linear geometries.