Abstract
A model for obtaining the σ-only effect on the nucleus-independent chemical shift (NICS) is introduced. By subtracting the values obtained for the “σ-only” model from the respective values of the conjugated system it is possible to obtain the NICS values that originate from the π system only. This procedure allows obtaining a quantitative measure of the relative intensities of diatropic and paratropic ring currents in different systems with a built-in measure of their accuracy. The scope and limitations of the model are discussed.