High resolution infrared studies and quantum-chemical calculations on MnO3F

All fundamental bands of MnO3F have been investigated by high-resolution infrared spectroscopy. The analysis of the spectra provides improved molecular parameters for the ground state and new parameters for the v(i) = 1 excited states, including a complete set of accurate vibration-rotation coupling constants. Conventional nb initio treatments fail for MnO3F due to its pronounced multireference character. Gradient-corrected density functional theory predicts structural parameters, vibrational wavenumbers, and harmonic as well as anharmonic spectroscopic constants of MnO3F which are in good agreement with the available experimental data. (C) 1997 Academic Press.