Nuclear dynamics static Jahn-Teller effect

The stoi7 begins with studies of the molecular Jahn-Teller effect in the late 1950s [1-3]. The Jahn-Teller theorems themselves [4,5] are 20 years older and static Jahn-Teller distortions of elecbonically degenerate species were well known and understood. Geomebic phase is, however, a dynamic phenomenon, associated with nuclear motions in the vicinity of a so-called conical intersection between potential energy surfaces. 

The so-called cooperative Jahn-Teller effect is another occurance of the static distortions. Here, interaction, that is, cooperation between different crystal centers, make the phenomenon observable. Without interaction, the nuclear motion around each center would be independent and of a dynamic character. 

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