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Reaction path direction

To appreciate the special role of a conical intersection as a transition point between the excited and the ground state in a photochemical reaction, it is useful to draw an analogy with a transition state associated with the barrier in a potential energy surface in a thermally activated reaction (Figure 6.6). In the latter, one characterizes the transition state with a single vector that corresponds to the reaction path through the saddle point. The transition structure is a minimum in all coordinates except the one that corresponds to the reaction path. In contrast, a conical intersection provides two possible linearly independent reaction path directions. [Pg.318]

Here the Q are the generalized normal coordinates and the to are the associated harmonic frequencies. They are obtained at each point on the path by diagonalizing the force constant matrix for which the reaction path direction as well as directions corresponding to rotations and translations have been projected out. The projected force constant matrix has seven zero eigenvalues corresponding to overall rotations, translations, and the reaction path direction. It also has 3N-7 nonzero eigenvalues corresponding to vibrations transverse to the path. [Pg.61]

The reason for such behavior of the reaction coordinate lies in the fact that the reaction path direction cannot be rigorously determined in its starting or end points corresponding to either the reactants or the products (see Sect. 1.3.4). [Pg.22]


See other pages where Reaction path direction is mentioned: [Pg.396]    [Pg.183]    [Pg.252]    [Pg.303]    [Pg.299]    [Pg.171]    [Pg.312]    [Pg.357]    [Pg.303]    [Pg.303]    [Pg.171]    [Pg.65]    [Pg.321]    [Pg.299]    [Pg.400]    [Pg.423]    [Pg.486]    [Pg.185]    [Pg.2059]    [Pg.2061]    [Pg.127]   
See also in sourсe #XX -- [ Pg.316 ]




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