Ab initio MRD-CI study of the spectrum of the TeO molecule employing relativistic effective core potentials

Potential energy curves and properties of the low-lying electronic states of tellurium oxide have been computed using a configuration interaction treatment that includes the spin-orbit coupling interaction. Relativistic effective core potentials (RECPs) are used to describe the inner shells of both the Te and O atoms. Good agreement is obtained for the spectroscopic constants of the X1-X2(3)sigma-, a1delta, and b1sigma+ states for which experimental data are available. The ratio of the parallel and perpendicular b-X transition moments, as well as the radiative lifetime of the b state, was computed, and both results were also found to be in good agreement with measurement. The energetic order of the electronic states in TeO appears to be very similar to that observed for the isovalent O2 molecule, but the Rydberg valence-mixing effects that are so prominent in the latter's spectrum (e.g., for the Schumann-Runge bands) are totally absent in TeO.