Quantum calculations of energy disposal

In the exact quantum calculation of the dynamics of a reaction on a particular potential-energy surface, it is necessary to solve the Schrodinger equation for the scattering from all occupied internal states of the reagents to all possible internal states of the products as a function of the relative collision energy. This is a multichannel process in that many final product vibrational and rotational states may be populated from a 

All quantum calculations that have been performed so far have been for reactions involving only three atoms of the type A + BC, where two reactive outcomes AB + C and AC + B are possible. Even then, the calculations are of gigantic proportions and a usual simplification to restrict the reactants and products to motion in a line (ID calculations). Full three-dimensional (3D) calculations have only been performed for a limited number of reactions, viz. 

However, with the exception of a few coplanar studies, all other quantum calculations have been for ID systems. The extent to which ID calculations form a satisfactory basis to explain the energy disposal in chemical reactions varies from reaction to reaction and, in the absence of experimental information or more approximate calculations, is impossible to assess. Collinear calculations need to be transformed to three dimensions in an attempt to incorporate the effects of orbital and rotational angular momentum which are absent in the ID calculations and produce more realistic product energy distributions [149,150]. Such methods appear to work most effectively for reactions whose dynamics are predominantly collinear. 

More details of the types of exact and appropriate quantum methods and their application to various reactions may be found in the recent reviews by Connor [143], Light [151], Wyatt [152] and Walker and Light [153] and earlier references contained in these works. 

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