Semi-classical calculations of energy disposal

In cases where quantum calculations are too demanding because of the large number of reactant and product states that are coupled together, semi-classical methods might provide a tractable alternative. Semi-classical collision theory exploits the ease of solving Hamilton s classical equations for motion over a reaction potential energy surface to approximate the 

Whilst semi-classical theories have been successful in describing non-reactive processes such as elastic and inelastic scattering, they have had less impact on calculations for reactions. The majority of calculations have been for simple reactions such as H + H2, F + H2 or H + Cl2 which have been treated collinearly for the most part. The most successful use of semi-classical theory is for treating tunnelling and it has found use extending the scope of purely classical calculations by describing classically forbidden processes and threshold effects [156]. 

The reader is referred to the reviews of Child [157] and Connor [143] for detailed discussion and description of semi-classical theories and for references to earlier works on the subject. 

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