The jahn-teller effect

This paper surveys the present understanding of the Jahn-Teller effect and includes a historical review of the principal advances. The important role of the dynamic Jahn-Teller effect in many experimental phenomena has only recently been recognized, and the predicted effects have now been observed in a large number of systems. The dynamic Jahn-Teller effect also explains why a Jahn-Teller distortion does not appear in certain cases for which it was expected and for which its absence was a long-standing puzzle. A Jahn-Teller distortion or “static” Jahn-Teller effect occurs as a limiting case of the dynamic effect, in the limit of strong coupling, and criteria for this transition are presented.