On the Anharmonicity of Vibrations of Polyatomic Molecules. I

Abstract

Several simplifying assumptions concerning the vibrational potential energy of polyatomic molecules are discussed and tested by means of the available experimental material. One of these assumptions furnishes relations between the higher coefficients of the potential energy of molecules containing several equivalent bonds. If a molecule contains p equivalent bonds XY, the potential energy of the corresponding symmetric stretching vibration, and only of this one, can be approximated by means of a Morse function with the constants pD and a/ √p in the place of D and a. The anharmonicity factors of bending vibrations are small if the third‐order coefficient of the potential energy vanishes on account of the symmetry of the molecule.