Refined potential-energy surfaces for the (X)over-tilde(2)A" and (A)over-tilde(2)A' electronic states of the HO2 molecule

In a previous paper (G. Osmann et al. J. Mel. Spectrosc. 197, 262 (1999)) w e calculated ab initio the potential-energy surfaces of the ground (X) over tilde (2)A" and excited (X) over tilde (2)A' electronic states of the HO2 molecule; these two states correlate with a (2)Pi state at linearity and pa rticipate in a Renner effect interaction. In that paper, we also calculated the electric- and magnetic-dipole moment and transition-moment surfaces, a nd the spin-orbit coupling constant; we then simulated the (A) over tilde - -> (X) over tilde emission band system including both electric-dipole and m agnetic-dipole transitions. We now calculate more points on the surfaces to cover a wider range of bending geometries, and then refine the surfaces by fitting to rovibronic term values for both electronic states simultaneousl y. In the fitting we include levels having J values up to 9/2 and term valu es up to about 8000 cm(-1). In our calculation of the energy levels we allo w for the Renner effect and spin-orbit coupling by using our variational co mputer program RENNER. A good fitting to the data is obtained and as a resu lt we obtain an accurate representation of these two potential surfaces ove r an energy range of more than 1 eV. We tabulate the vibronic energies up t o 1 eV for both HO2 and DO2. We can explain the origin of a perturbation ob served in the F-1 spin component levels of the (A) over tilde (0, 0, 0) vib ronic state for J values around 51/2; this is caused by a spin-orbit intera ction satisfying DeltaN = +/-1 with the F-2 spin component levels of the (X ) over tilde (1, 1, 2) vibronic state. Using the new rovibronic energies an d wave functions, with our ab initio electric dipole moment and transition moment surfaces, we calculate Stark coefficients and compare them with expe riment for some ground vibronic state levels.