Symmetry-based method for the derivation of the vibration–rotation kinetic energy operator and energy levels calculation of carbonyl fluoride from a new ab initio potential energy surface

Abstract

A simple and intuitive symmetry-based method for deriving the vibration–rotation kinetic energy operator (in polyspherical coordinates) for a general polyatomic molecule using the kinetic energy of a triatomic molecule was considered. Two vectors define the molecule-fixed coordinate system. For example, those vectors can determine positions of two atoms with respect to the third atom. By rotating the coordinate system, it is possible to obtain expressions that relate coefficients determining the kinetic energy in two coordinate systems. Those expressions let us obtain formulas for kinetic energy of general polyatomic molecules from kinetic energy of the triatomic molecules. Vibrational Energy levels of COF2 molecules were calculated from new ab initio potential energy surface. The comparison of the calculated and experimental vibrational energy levels is also reported.