Operator formulation of the diatomic partition function

Abstract

Some operator trace formulae are used in the discussion of the diatomic rotation-vibration partition function in ¹Σ-states for ideal gases. Starting with the power series expansion of the potential energy the partition function is calculated by forming traces of exponential operators. The occupation number representation is particularly well suited for this purpose. The aim of this paper is to test the validity of the method for the thoroughly investigated diatomic molecule and for its further application to polyatomic molecules.