application of Hund's rules would suggest the ordering 3F < 3P < 1G < 1D < 1S. In reality, however, 1D lies below 1G. References External links A glossary entry hosted on the web site of the Chemistry Department of Purdue University A PhysicsWeb article Multiplets in Transition Metal ions in E. Pavarini, E. Koch, F. Anders, and M. Jarrell: Correlated Electrons: From Models to Materials, Jülich 2012, E. Scerri, The Periodic Table, Its Story and Its Significance, 2nd ed. (Oxford University Press, 2020) Atomic physics Quantum chemistry Spectroscopy Rules