Jahn-Teller intersection

The first thing to be done when applying the theory is to identify the e and o reaction paths. One can then proceed to calculate and iPn, and then to extract If e and using Eq. (6). In H - - H2, the form of the potential energy surface is very well characterized [50-53], and the form of the Cl is a standard example of an E X e Jahn-Teller intersection. 

In Fig. 3 we show a cross section of the Jahn-Teller surface around the tetrahedral geometry. The simplest Jahn-Teller intersection is of T t2 type (i.e., a triply degenerate electronic state whose components are coupled via a triply-degenerate vibration). Optimization of a triply degenerate conical intersection is not routinely possible at present. The vibrational modes of Td Fe(C0)4 span Qa 2 1 2E T 4T2, so there are clearly several candidate vibrations. This T t type of... 

Fig. 9 Snapshots of sample Cr(CO)j trajectory (viewed down axial ligand axis) through trigonal bipyramid Jahn-Teller intersection (reached in 130 fs), followed by oscillation in square planar (SP) well of Jahn-Teller trough . Saddle-point like stracture is shown after 200 fs, followed by SP like stracture after 360 fs...

The canonical vibrational coordinates forFe(CO)4 (7)/) are QsN-e e 2Ai 0 2 0 Ti 4T2, and clearly there are many possible Jahn-Teller models including E(g>e, Tt, (T E)t, (T0ii)(8)(r0e). We have investigated in detail the T (git Jahn-Teller intersection in the singlet manifold, in addition to the triplet manifold (i.e., for both the T2 and states). This is because in the triplet manifold there exists a substantial amount of experimental work. However, bearing in mind that quantum chemistry predicts a lower E state the more complex Jahn-Teller models will also have to be investigated in detail as well. 

For a polyatomic molecule with n degrees of freedom, the crossing point is replaced by a crossing seam in a ( - l)-dimensional space or, for certain symmetric systems, is replaced by canonical or Jahn-Teller intersection (see chapter 3). Such nonadiabatic interactions for polyatomics have been studied extensively by Lorquet and co-workers (Desouter-Lecomte et al., 1979 Dehareng et al., 1983 Desouter-Lecomte et al., 1985 Barbier et al., 1984). 

Intersections are symmetry-required when the two electronic states form the components of a degenerate irreducible representation. The Jahn-Teller intersection of the two lowest electronic states in Nas which correspond to the components of an E irreducible representation of the point group Csv, provides an example of this class of conical intersection. Conical intersections which are not required by symmetry are accidental intersections. Accidental symmetry-allowed different symmetry) intersections correspond... 

JAHN TELLER AND PSEUDO-JAHN TELLER INTERSECTIONS SPECTROSCOPY AND VIBRONIC DYNAMICS... 

Jahn Teller and Pseudo-Jahn—Teller Intersections... 

Jahn—Teller and Pseudo-Jahn-Teller Intersections... 

H. Koppel, Jahn-Teller and pseudo-Jahn-Teller intersections Spectroscopy and vibronic dynamics, in Conical Intersections, Electronic Structure, Dynamics and Spectroscopy, W. Domcke, R. Yarkony, H. Koppel, Eds., World Scientific, Singapore, 2004, pp. 429 72. 

Desouter-Lecomte, M., Galloy, C., Lorquet, J.C., and Vaz Fires, M. (1971) Nonadiabatic interactions in unimolecular decay. V. Conical and Jahn—Teller intersections./. Chem. Phys., 71, 3661. 

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