A distributed model of the electrical response of organic molecules

Correlated ab initio calculations of the electrical properties of a large set of organic molecules have been carried out and used in the selection of transferable parameters in an additive model of electrical response. The set of parameters of the model consists of anisotropic atomic dipole polarizabilities for H, C, N, O, and F atoms in different bonding environments and bond dipole moments. The model uses a distribution of atomic dipole polarizabilities and bond dipoles according to the bonding and structure of a molecule. The model describes a molecule's long-range electrostatic potential and the change in that potential from polarization by an external electrostatic potential. To very good accuracy, it yields mean molecular dipole polarizabilities and magnitudes of dipole moments, and to good accuracy, it yields dipole polarizability anisotropies and dipole moment orientations. The capability of the model reinforces the idea that to a good extent molecular polarization is tied to electronic structure changes at individual atoms. Ultimately, this will aid in modeling the effects of polarization response on other properties.