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.