An atomic capacitance-polarizability model for the calculation of molecular dipole moments and polarizabilities

A classical interaction model for the calculation of molecular polarizabilities has been investigated. The model is described by atomic capacitancies, polarizabilities, and a parameter related to the size of the atom, where one set of parameters has been employed for each element. The model has been parameterized for the elements H, C, N, O, F, and Cl from quantum chemical calculations of the molecular polarizability and dipole moment for 161 molecules at the Hartree-Fock level. The atomic charge has been divided into a nuclear charge and an electronic contribution, which also allows for modeling the permanent molecular dipole moment. Results are presented for polyenes. Excellent agreement with quantum chemical calculations is obtained for the components of the polarizability perpendicular to the chain, but the results are less satisfying for the component along the chain. An inherent deficiency of using atomic capacitancies for large molecules and long chains is discussed.