Normal Vibration Frequencies of the Molecule XYZ3

Abstract

A very general expression is set up for the potential energy of the tetrahedral molecule XYZ₃. The normal vibration frequencies are given as functions of the constants in this expression. The equation for the parallel frequencies is shown to be essentially independent of the shape of the tetrahedron, while for the perpendicular case the two angles determining the molecular configuration must be taken into account. Connections are given between the general potential energy constants and the constants for the special forces used by Dennison and Sutherland.