The Fragments-in-Molecules Method Ill. Inductive and Mesomeric Effects*

Within the framework of the recently developed FIM method the interaction of FO's is evaluated in two steps: inductive perturbations are calculated on the basis of the generalized product approach treating each fragment in the field of all other fragments. The mesomeric interactions in the composite system are then obtained from SCF calculations based on these FO's. Applications to re systems based on the PPP approximation as well as applications based on the CND0/2 approach show that this definition of inductive and mesomeric effects is quite natural and useful in discussing the electronic structure of organic molecules.