Adiabatic channel potential curves

Figure 1. Adiabatic channel potential curves V,(r) for the interaction between Hj and HC1 (calculations for (j,m,l) = (0, 0, /) with / = 0, 40, 60 from Ref. 15 full curves real potential dashed curves locked-dipole potential used in PST).

The locked permanent-dipole capture system may serve as our first example for an isotropic potential where SACM and PST coincide. In this case, the adiabatic channel potential curves have the form... 

As a second example we analyze the anisotropic charge-permanent dipole potential where SACM and PST differ from each other. Here, for demonstration, we only consider the low-energy perturbation and the high-energy harmonic oscillator limits. In the former limit, the adiabatic channel potential curve for the lowest channel j = m = 0 has the form... 

More complicated anisotropies of the potential are, for example, encountered in the association of two linear dipoles. Adiabatic channel potential curves for this case have been calculated and expressed analytically in Ref. 16. More systematic studies, also comparing SACM and trajectory results, were reported in Ref. [36], One may as well consider open-shell effects for example, the association of two open-shell HO radicals in their lowest rotational state was treated in Ref. 37. Figure 12 shows the lowest rovi-bronic adiabatic channel potential curves for this system. The ultimate goal... 

Figure 7. Lowest adiabatic channel potential curves for the interaction of C+ with OH(2I1q ) (curves labeled by rotational quantum numbers m for given j, II SACM calculations from Ref. 9).

Figure 8. Lowest adiabatic channel potential curves [33] for the interaction of electronic ground state N2 with ions (q = ionic charge, Q = N2 quadnipole moment N, M = free-rotor quantum numbers k,v = harmonic oscillator quantum numbers for more details, see Ref. 33).

Figure 12. Lowest rovibrational adiabatic channel potential curves of two interacting OH(2Il3/2) radicals [classified in fvTis, k) nomenclature, s = +1 states shown see Ref. 37].

A.I.Maergoiz, E.E.Nikitin, and J.Troe, Adiabatic channel potential curves for two linear dipole rotors II. Analytic representation of channel potentials and rate expressions, Z. phys. Chem. 172, 129 (1991)... 

Maergoiz AI, Nikitin EE, Troe J. (1991) Adiabatic channel potential curves for two linear dipole rotors. I. Classification of states and numerical calculations for identical rotors. J. Chem. Phys. 95 5117-5127. 

Transition-state switching may also occur in SACM, either for single-channel potential curves or for groups of channels such as in microcanonical variational versions with adiabatic channel states. 

The PES for HNO does not have a barrier between the well region and the exit channel furthermore, the TS is quite loose so that also the potential curves for the lowest adiabatic vibrational-rotational states are purely attractive at large and intermediate H-NO distances (see Fig. 8 of Ref. 34). Therefore it does not come as a surprise that the dissociation starts right at the threshold with rates that are large compared to HCO (Fig. 7). As for HCO... 

In chapter 7 the statistical adiabatic channel model (SACM) (Quack and Troe, 1974, 1975) was described for calculating unimolecular reaction rates. This theory assumes the reaction system remains on the same diabatic potential energy curve while moving from reactant to products. Two parameters, a and (3 are used to construct model diabatic potential curves. The unimolecular rate constant, at fixed E and 7, for forming products with specific energy , (e.g., a specific vibrational energy in one of the fragments) is... 

Such quantum capture theories in three dimensions have been developed to solve the Schrodinger equation for the long-range attractive entrance channel potential in a coupled rotational-states formalism. A rotationally adiabatic approximation to this theory has been developed by constructing potential curves that describe the evolution of... 

In this case, the so-called statistical theory of adiabatic channels is used. In this theory, the vibration-rotational energy levels corresponding to the certain J are calculated at each specified value of the reaction coordinate q. The examples of such potential curves are shown in Fig. 4.12, where W(s + Asj (J)-Ee) is identified with the total number of such potential curves along which with the specified total energy = s + aj one can get into the region of decomposition products. 

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