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Nonadiabatic reaction path

The results obtained in a study of the reactions of one of the same cryptands, Eu(2.2.1) , with the excited states of a series of poly(pyridine)Ru(II) complexes show a qualitative agreement with the previous study. The detailed analysis of the data by Sabbatini et al. (1986), however, invokes the availability of nonadiabatic reaction paths for the cross reactions. The fact that in this later study, the thermody-... [Pg.386]

It has been shown that there is a two-dimensional cut of the PES such that the MEP lies completely within it. The coordinates in this cut are 4, and a linear combination of qs-q-j. This cut is presented in fig. 64, along with the MEP. Motion along the reaction path is adiabatic with respect to the fast coordinates q -q and nonadiabatic in the space of the slow coordinates q -qi-Nevertheless, since the MEP has a small curvature, the deviation of the extremal trajectory from it is small. This small curvature approximation has been intensively used earlier [Skodje et al. 1981 Truhlar et al. 1982], in particular for calculating tunneling splittings in (HF)2- The rate constant of reaction (6.45a) found in this way is characterized by the values T<. = 20-25 K, = 10 -10 s , = 1-4 kcal/mol above T, which compare well with the experiment. [Pg.132]

Thus we adopt the view (see suggested reading 1) that any structure along the reaction path is an intermediate. With modern laser spectroscopy (suggested reading 2), one can now directly probe such structures experimentally. Thus it is a reactive intermediate, because it can be seen spectroscopically, not because it can be put in a bottle for a short time. As we shall see, this revised view of an intermediate is particularly relevant for photochemical and other nonadiabatic processes. [Pg.380]

Electron nuclear dynamics theory is a direct nonadiabatic dynamics approach to molecular processes and uses an electronic basis of atomic orbitals attached to dynamical centers, whose positions and momenta are dynamical variables. Although computationally intensive, this approach is general and has a systematic hierarchy of approximations when applied in an ab initio fashion. It can also be applied with semiempirical treatment of electronic degrees of freedom [4]. It is important to recognize that the reactants in this approach are not forced to follow a certain reaction path but for a given set of initial conditions the entire system evolves in time in a completely dynamical manner dictated by the interparticle interactions. [Pg.327]

Fig. 1V-I. Correlation diagram for the reactions O + N2 and NO + N. C, symmetry is assumed for the reaction intermediate. Three reaction paths are available for O (3P) + N2, five for O( 0) + N2,andoneforO( 5) + N2. Quenching of O( S) by N2 is probably physical and would require a high energy barrier, while quenching of O(lD) to 0(3P) is facilitated by nonadiabatic crossing from A to 3A + 23A" surfaces. Reprinted with permission from Donovan and Husain, Chem. Rev., 70, 489 (1970). Copyright by the American Chemical Society. Fig. 1V-I. Correlation diagram for the reactions O + N2 and NO + N. C, symmetry is assumed for the reaction intermediate. Three reaction paths are available for O (3P) + N2, five for O( 0) + N2,andoneforO( 5) + N2. Quenching of O( S) by N2 is probably physical and would require a high energy barrier, while quenching of O(lD) to 0(3P) is facilitated by nonadiabatic crossing from A to 3A + 23A" surfaces. Reprinted with permission from Donovan and Husain, Chem. Rev., 70, 489 (1970). Copyright by the American Chemical Society.
We have shown that an accessible conical intersection forms a bottleneck that separates the excited state branch of a nonadiabatic photochemical reaction path from the ground state branch, thus connecting the excited state reactant to two or more products on the ground state surface via a branching of the... [Pg.113]

Nonadiabatic Feshbach calculations. Using the reaction-path Hamiltonian and invoking an adiabatic separation of the reaction coordinate from all other coordinates, resonance energies and adiabatic partial widths are obtained by neglecting all off-diagonal terms of the Hamiltonian. The most important... [Pg.384]


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