A DISTRIBUTED MODEL OF THE ELECTRICAL RESPONSE OF ORGANIC-MOLECULES

Correlated ab initio calculations of the electrical properties of a la rge set of organic molecules have been carried out and used in the sel ection of transferable parameters in an additive model of electrical r esponse. The set of parameters of the model consists of anisotropic at omic dipole polarizabilities for H, C, N, O, and F atoms in different bonding environments and bond dipole moments. The model uses a distrib ution of atomic dipole polarizabilities and bond dipoles according to the bonding and structure of a molecule. The model describes a molecul e's long-range electrostatic potential and the change in that potentia l from polarization by an external electrostatic potential. To very go od accuracy, it yields mean molecular dipole polarizabilities and magn itudes of dipole moments, and to good accuracy, it yields dipole polar izability anisotropies and dipole moment orientations. The capability of the model reinforces the idea that to a good extent molecular polar ization is tied to electronic structure changes at individual atoms. U ltimately, this will aid in modeling the effects of polarization respo nse on other properties.