ENERGY LEVELS OF POLYATOMIC MOLECULES. PART ONE.

The rotation-vibration energies of polyatomic molecules were computed to the fourth order of approximation. These energies are used to obtain the frequencies of lines in rotation and rotation-vibration spectra. Such very accurate calculations are necessary in order to explain many effects observed in very high resolution spectra. The following topics are emphasized the quartic anharmonic potential function the rotation spectrum of axially symmetric molecules in an excited vibrational state the rotation-vibration spectra of spherical top molecules anomalous rotational structure of level 0311 in the rotation-vibration spectrum of C13 O216 rotational structure of the fundamental NU6 of methyl cyanide a general discussion of Fermi resonance in CO2 with a new assignment of vibrational levels.