There are 8 distance classes (class 0: 0-6.0Å, class 1: 6.0-9.5Å, etc.). The number of classes cannot be changed. The given values for the distance criterions (e.g., 6.0, 9.5, etc.) are default values chosen by the utility program xpl2lis. In general, if one choses larger values for these distance criterions the calculation of the electrostatic interactions is more accurate but also more compuational effort is needed. Usually, these values do not have to be changed and are a good tradeoff between accuracy and computational effort.