User talk:Paul Wormer/scratchbook1

The Jahn-Teller effect is the distortion of a highly symmetric—but non-linear—molecule to lower symmetry and lower energy. The effect occurs if the molecule is in a degenerate state of definite energy, that is, more than one wave function is eigenstate with the same energy of  the molecular Hamiltonian. In other words, energy degeneracy of a state implies that two or more orthogonal wave functions describe the state. Due to Jahn-Teller distortion, the molecule is lowered in symmetry and the energy degeneracy is lifted. One or more wave functions become non-degenerate eigenstates of lower energies, while others wave function rise in energy.

The effect is named after H. A. Jahn and E. Teller who predicted it in 1937. It took some time before the effect was experimentally observed, because it was masked by other molecular interactions. However, there are now numerous unambiguous observations that agree well with theoretical predictions. These range from the excited states of the simplest non-linear molecule H3 through moderate sized organic molecules, like ions of substituted benzene, to complex crystals and localized impurity centers in solids.

 The Jahn-Teller effect is based on a quantum mechanical mechanism and no classical description of it exists. From here on some knowledge of quantum mechanics is prerequisite to the reading of this article.