Semiclassical theory for the quantum defect function of diatomic molecules

Abstract

The simple analytical expression for the quantum defect function, Δlm(R),of a diatomic molecule is derived using the uniform semiclassicalapproach including the effects of hidden crossing. Δlm(R) is a function ofthe internuclear distance Rand the effective charge at each nucleus is also a function ofR. Thus,in the case of homonuclear molecules this expression gives universal dependenceon R.The derived expression is applied to H2molecules. The quantum defects are found to be in good agreement with the abinitio numerical data by Wolniewicz and Dressler (1994 J. Chem. Phys. 100 444).