Vibrations of Symmetrical Tetratomic Molecules

Abstract

The general method for obtaining the vibration frequencies of any symmetrical molecule is outlined, and the results of its application to the tetratomic case are given. The frequencies are derived for the most general force field consistent with geometrical symmetry and also for a more specific case based on a simplified model. It is shown that the assumption of the rigidity of the bonds requires two different forces perpendicular to the lines of bond. The coplanar tetratomic and the collinear triatomic molecules are found to be the only ones of a number of molecules investigated so far, where an unambiguous determination of the physical force constants is possible. In the general case, no very definite meaning can, apparently, be attached to terms like "magnitude of bond constant."