Digital simulation of potential step experiments using the extrapolation method

For large values of the model diffusion coefficient the Crank-Nicolson scheme produces poor numerical results, if it is used for the simulation of a potential step experiment. On the other hand the Backward Euler or fully implicit scheme, not suffering from this drawback, is of lower accuracy. We apply the extrapolation method introduced by Morris et al. to the simulation of Cottrellian diffusion and to a simple catalytic mechanism. The extrapolation method, does not show the oscillating behavior of numerical solutions and is of higher accuracy than the fully implicit scheme. Comparison to other implicit difference schemes are presented. The extrapolation schemes show superior results for the diffusional problem and for the short time behavior of the catalytic mechanism.

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