Intermolecular interactions: Elaboration on an additive procedure including an explicit charge‐transfer contribution

An additive procedure is derived for the computation of intermolecular interactions, in which an explicit expression for the charge‐transfer energy contribution E CT is implemented. In the total interaction energy, the electrostatic terms E MTP and E pol are calculated as in our previous treatment. The dispersion contribution is calibrated by reference to variation‐perturbation computations on model systems and the repulsion contribution is computed as a sum of bond—bond, bond—lone pair, and lone pair—lone pair interactions. Tests of the procedure are given for representative hydrogen‐bonded systems.