Correlated walk in the presence of an external field is applied to the study of diffusion coefficients in simple cubic lattices. A continuous time distribution is introduced with the aid of the pausing time distribution developed by Montroll. An exact expression for the diffusion coefficient is derived for perfect cubic lattices. It is found that the external field attenuates the effects of the rms deviations. These results are used to discuss the atomic diffusion in cubic lattices with impurities, which act as traps. Comparison with previous experimental and theoretical results is made and discussed.
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