Electronic structure and bonding of ozone.

The ground and low-lying states of ozone (O₃) have been studied by multireference variational methods and large basis sets. We have constructed potential energy curves along the bending coordinate for (1,2) ¹A^′, (1,2) ¹A^″, (1,2) ³A^′, and (1,2) ³A^″ symmetries, optimizing at the same time the symmetric stretching coordinate. Thirteen minima have been located whose geometrical and energetic characteristics are in very good agreement with existing experimental data. Special emphasis has been given to the interpretation of the chemical bond through valence-bond-Lewis diagrams; their appropriate use captures admirably the bonding nature of the O₃ molecule. The biradical character of its ground state, adopted long ago by the scientific community, does not follow from a careful analysis of its wave function. [ABSTRACT FROM AUTHOR]