Nondirect product basis

A nondirect product basis expansion method described in the previous section on gas-phase reaction, similar to the spirit of L-shaped grid method proposed by Mowrey (91), is also used in gas-surface reactions. This method is actually ideal for gas-surface reaction because the skewing angle of the PES is strictly 90° (see Fig. 14). A collinear model study showed explicitly that the required number of quasiadiabatic diatomic vibrational function is only larger near the potential saddle point region (92). Based on the treatment of non-direct product basis described in the previous section (Eq. 89), the translation basis function is given by... 

In gas-phase dynamics, the discussion is focused on the TD quantum wave packet treatment for tetraatomic systems. This is further divided into two different but closed related areas molecular photofragmentation or half-collision dynamics and bimolecular reactive collision dynamics. Specific methods and examples for treating the dynamics of direct photodissociation of tetraatomic molecules and of vibrational predissociation of weakly bound dimers are given based on different dynamical characters of these two processes. TD methods such as the direct projection method for direct photodissociation, TD golden rule method and the flux method for predissociation are presented. For bimolecular reactive scattering, the use of nondirect product basis and the computation of the initial state-selected total reaction probabilities by flux calculation are discussed. The descriptions of these methods are supported by concrete numerical examples and results of their applications. 

Czako, G., Szalay, V, Csaszar, A.G. Finite basis representations with nondirect product basis functions having structure similar to that of spherical harmonics, J. Chem. Phys. 2006,124, 014110. 

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