III. Homonuclear Diatomics: Second-Row Elements 14 A. The diatomic boron molecule 16 1. Σg state 16 2. Σg state 19 B. The diatomic oxygen and carbon molecules in their lowest states 20 1. O2 20 2. Reflection symmetry 21 3. Electron repulsion 23 4. MCSCF calculations for O2 24 5. The C2 molecule 25 C. Spectroscopic notation for diatomic molecules 28 D. States of other homonuclear diatomic molecu...

The inversion symmetry of a system causes non-local, coherent behaviour of the otherwise localized core holes in homonuclear diatomic molecules such as N2. This non-locality of the electron emission and the remaining core hole changes in a continuous way into partially localized behaviour if a gradual breakdown of the inversion symmetry is induced by isotope substitution. This is reflected by t...

In the present article, we introduce a model to investigate the energy spectrum of a relativistic rotor by considering the Klein-Gordon Hamiltonian. Rotational spectral lines are a signature of homonuclear and heteronuclear systems and play a key role in understanding diatomic molecules. We show that the energy-correction term arising due to unequal masses influences the line separation. Determ...