CONFIGURATIONAL, SPIN IN THE THEORY OF VIBRATION-ROTATION SPECTRUM OFA NONRIGID MOLECULE

The notion of configurational spin is introduced to describe the confi gurational degeneracy in the vibration-rotation spectrum of a nonrigid molecule, i.e., the degeneracy that is due to the presence of several independent and energetically equivalent equilibrium configurations. The NH3 molecule, which has two such configurations related by inversi on, is used to analyze the algebraic and symmetric properties of the s pin. The qualitative construction of the operators of the observables on the basis of this spin is discussed.