Seam of intersection

The plot of the energy along 2xi and 2 3 in the second order picture is shown in Fig. 4b. In this case, the seam of intersection is a curved tine. The energy degeneracy is kept by combined displacements along and 2x3, and the first condition of von Neumann and Wigner (Equation 2) becomes ... 

The search for conical intersections, avoided crossings and seams of intersection between two PESs are also tasks involving optimization [115-123]. If the two surfaces represent different spin states or have different spatial symmetry, they can cross. If they are the same symmetry and spin, they can interact and the crossing is avoided. Where the matrix element coupling the two surfaces is zero, they touch and give rise to a conical intersection, as illustrated in Eig. 10.3. To study the mechanisms of photochemical reactions, we often wish to hnd the lowest energy point on a seam or conical intersection. For a seam of intersection between two adiabatic surfaces and E2, we require ] = Ei-Since a (non-linear) molecule has 6 internal degrees of freedom, a seam of... 

Figure 2.11 Potential energy surface for an ( -l)-dimensional seam of intersection in the intramolecular excitation-energy transfer of BOD.

However, in some cases the avoided crossing path merges with the conical intersection, and the crossing becomes, effectively, a seam of intersection such as the one shown in Figure... 

The general description of the conical intersections for ET goes along the lines used to describe the model peaked intersection in Figure 2.7 and the seam of intersection in... 

Fig. 1. Three-dimensional perspective plot of the adiabatic potential energy surfaces of the double-sheeted ground electronic state of H3 in the (R,r) plane for 7 = tt/2, corresponding to the C 2v arrangements of the three nuclei. The contour line diagram is included in the base of the plot. The spacing between the successive contour lines is 0.3 eV. The potential energies are obtained from the DMBE PES and the lower (y ) and the upper (V ) adiabatic sheets are shown by the thin and thick solid curves, respectively. The conical intersection of the two surfaces should not be realized as an isolated point as apparently revealed by the perspective plot, rather, it represents a seam of intersections occurring for R = which is more clearly indicated by the...

Asturiol D, Lasorne B, Worth GA, Robb MA, Blanceifort L. Exploring the sloped-to-peaked S2/S1 seam of intersection of thymine with electronic structure tind direct queintum dynamics. Phys Chem Chem Phys 12 4949... 

Fig. 7.11 Cartoon of the two radiationless decay mechanisms for the cyanine model. The white line represents the seam of intersection between the Si and So potential energy surfaces (from [90])...

Reaction (20) cannot occur on adiabatic surfaces of CUv or 2v symmetry because the reactants correlate with or Aj and the products with Ifl or B2. However, the and B2 surfaces (Figs. 3,4) intersect and the seam of intersection is shown in Fig. 3. On distortion to Q symmetry both surfaces transform to and the intersection will be avoided. Thus a trajectory which starts on the surface correlating with A in C2v pan readily reach the surface correlating with B2 resulting in the formation of A1H (A 2 ]) + h. 

Rx(3.7294). From this table the following are evident. The molecule has only Cj symmetry since y 45°, The points on the seam of intersection are all exoergic relative to the reactant asymptote in equation (75) and therefore serve as a funnel for that collisional quenching process. 

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