Pseudo-Jahn-Teller Effect

[William D Hobey <whobey;at;WPI.EDU>]

 In reply to Anton Van Oosten's question, I interpret the Jahn-Teller Effect
 as the coupling of two degenerate electronic states through a vibrational
 mode of motion, while the Pseudo-Jahn-Teller Effect is the coupling of two
 nearly degenerate electronic states through a vibration. Mathematically,
 the only difference is that the diagonal matrix elements (in, say, a
 perturbation treatment) are equal in one case, and differ to a "small"
 extent (of the order of vibrational energies) in the other. Physically,
 there appears to be no significant difference between the two cases. For
 basic theory see
 W.D.Hobey and A.D.McLachlan, "Dynamical Jahn-Teller Effect in Hydrocarbon
 Radicals", J. Chem. Phys. 33, 1695 (1960).
 For a simple minded application, see
 W.D.Hobey, "Vibronic Interactions of Nearly Degenerate States in
 Substituted
 Benzene Anions", J. Chem. Phys. 43, 2187 (1965).
 				Bill Hobey