All the nonadiabatic (J=0) bound states of NO2

We calculated all 3170 A1 and B2 (J=0) vibronic bound states of the coupled electronic ground (X̃ 2A1) and the first excited (Ã 2B2) surfaces of NO2, using a modification of the ab initio potentials of Leonardi et al. [J. Chem. Phys. 105, 9051 (1996)]. The calculation was performed by harmonic inversion of the Chebyshev correlation function generated from a DVR Hamiltonian in Radau coordinates. The rms error of the eigenenergies is about 2.5 cm−1, corresponding to a relative error of 10−4 near the dissociation energy. The results are compared with the adiabatic and diabatic levels calculated from the same surfaces, with experimental data, and with some approximations for the number of states function N(E). The experimental levels are reproduced fairly well up to an energy of 12 000 cm−1 above the potential minimum while the total number of bound levels agrees to within 2% with that calculated from the phase space volume.