It is widely accepted that the ions and water molecules do not have the same mobility or diffusivity in confined regions as in bulk. In fact, it is more likely to have a lessening in the effective mobility of ions in ion channels. In reduced particle methods where the channel water is assumed as implicit continuum background, a mean ion mobility is needed to reveal how ions could diffuse due to local electrostatic forces and random events. In Transport Monte Carlo simulations, the total scattering rate ( λ λ ), is assumed to only result from ion-water interactions; it is related to ion diffusivity with the expression