QUANTITATIVE-DETERMINATION OF THE TOTAL LOCAL POLARITY (CHARGE SEPARATION) IN MOLECULES

We introduce a polarity index-PI that is proposed as a measure of the charge separation in a molecule. PI can be viewed as the average deviation of the electrostatic potential on the surface of the molecule. It permits a quantitative assessment of total local polarity, even in a molecule that has zero dipole moment. In support of our formulation of PI, we show that it is related to an empirical polarity-polarizability parameter and also to the dielectric constant.