Definition of configuration (electronic)

1. A distribution of the electrons of an atom or a molecular entity over a set of one-electron wavefunctions called orbitals, according to the Pauli principle. From one configuration several states with different multiplicities may result. For example, the ground electronic configuration of the oxygen molecule (O2) is

   1g2, 1u2, 2g2, 2u2, 1u4, 3g2, 1g2

   resulting in the

   3g, 1g, and 3g+ multiplets

   IUPAC PHOTOCHEMICAL GLOSSARY (1992).