Many-Modes Jahn-Teller Effect home | Theory Group

Dynamic Jahn-Teller:

a degenerate electronic state interacting with one or several vibrational modes, also degenerate. One mode only: a well understood problem (but no global exact solutions - yet!). A BO potential surface with a flat minimum trough and a diabolic intersection in the high-symmetry point corresponding to the undistorted molecular configuration.

Many modes at the same time:

We find the exact semiclassical (strong coupling) zero-point energy shifts applicable to the E × (n e) and T × (n h) dynamic Jahn-Teller problems, for an arbitrary number of discrete vibrational modes simultaneously coupled to one single electronic level. We also obtain an analytical formula for the frequency of the resulting NEW normal modes, which has an attractive and apparently general Slater-Koster form. The limits of validity of this approach are assessed by comparison with O'Brien's previous effective-mode approach, and with accurate numerical diagonalizations. Fullerene negative ions have a three-fold degenerate electronic level interacting with n=8 h vibrational modes. We insert the coupling constants appropriate to C60- in our theory of T × (n h), and compare the results with experimental data.

Those interested may read more in N. Manini and E. Tosatti, Phys. Rev. B 58, 782 (1998). Early results and an introduction to molecular JT effect may be read in Manini's PhD thesis.