Conical intersections orthogonal intersection adapted

The lowest order contributions to the energy are described by the conical parameters g, h, and s, k = x,y,z, or by d, A = 1,2 and s, k = x,y,z-Here and below the superscript ij is suppressed when no confusion will result. We also will use the nonrelativistic convention g - x,fi" y and h J z, where is real is parallel to. These parameters [9] are reported in Figure 4a and b. Their continuity is attributable to the use of orthogonal intersection adapted coordinates. For comparison, Figure 4a and b reports the nonrelativistic quantities g , and s, respectively. While noting that there is no unique correspondence... 

Figures 6(a) and 6(b) report the conical parameters Sy and g, h, respectively, obtained from orthogonal intersection adapted coordinates. If orthogonal g and h had not been used g and h would vary erratically along the path, making interpolation and extrapolation impossible. Significantly, from Figs. 6(a) and 6(b), it can be seen that although these conical parameters are by no means constant, the inequalities > g > h, discussed above for Tl trans,p, 2.95), are, in a qualitative sense, typical.

Figure 3.1 Schematic representation of photochemical reaction involving a conical intersection. The X axis corresponds toXs the "reaction path," which is a representative coordinate orthogonal to the branching space Xi X2. The Y axis (X1/2) is a compound coordinate, corresponding to a vector that lies in the plane spanned by X, X2. Photoexcitation from the ground-state geometry, GSi, leads to the excited-state potential energy surface at point EXq. The excited-state branch of the reaction coordinate continues to various points on the conical-intersection seam Cl, and CI2. At this point decay occurs in the branching space Xi X2 at the double cone shown inset and the reaction path continues on the ground state toward possible products GSt and GS2. Adapted from Serrano-Perez et al. ...

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