Diffusion on a Sphere IRT Algorithm

The relative diffusion equation for two particles (one static and the other mobile) evolves under the influence of an angular diffusion equation of the form 

The required boundary condition is that of Smoluchowski (i.e. particles react instantly on encounter at a critical value f) such that 

Using the method of separation of variables, N. J. B. Green (unpublished) has obtained the general solution for the survival probability S2(f) to be 

To ensure firstly that the recombination kinetics was accurately modelled in the IRT framework, the IRT simulation was compared with the analytical expression [24] as obtained by McQuarrie 

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