In polymers and solids, a cutoff distance, in Ångstroms, is needed in order to ensure that every atom has a correct electric environment. If no cutoff is set, then equivalent atoms would experience different electric fields. The CUTOFP distance is set, by default, to the largest distance that would ensure that equivalent atoms experience the same potential. In calculating the potential due to distance atoms, atoms separated by more than CUTOFP are treated as if they were at distance CUTOFP.