Accurate ab initio near-equilibrium potential energy and dipole moment functions of the ground electronic state of ozone

We report a highly correlated multireference configuration interaction calc ulation of the near-equilibrium potential energy surface of ozone using a l arge correlation consistent basis set. Three-dimensional analytical express ions are obtained for the potential energy and dipole moment functions usin g least-squares fits to ab initio points near the C-2v equilibrium geometry . Low-lying vibrational band origins of O-16(3) and some of its isotopic va riants are calculated using the ab initio potential energy function. The ca lculated fundamental frequencies for the symmetric stretching and bending v ibrations are within about 3 cm(-1) of the observed values, while that for the antisymmetric stretch deviates from experiment by about 13 cm(-1). The agreement with experiment can be significantly improved if the ab initio po tential energy function is scaled in the antisymmetric stretching coordinat e. Absolute infrared absorption intensities are also calculated using ab in itio electric dipole moment functions and in good agreement with the availa ble experimental data. (C) 2000 American Institute of Physics. [S0021-9606( 00)30219-7].