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

A classical interaction model for the calculation of molecular polarizabili ties has been investigated. The model is described by atomic capacitancies, polarizabilities, and a parameter related to the size of the atom, where o ne set of parameters has been employed for each element. The model has been parameterized for the elements H, C, N, 0, F, and Cl from quantum chemical calculations of the molecular polarizability and dipole moment for 161 mol ecules at the Hartree-Fock level. The atomic charge has been divided into a nuclear charge and an electronic contribution, which also allows for model ing the permanent molecular dipole moment. Results are presented for polyen es. Excellent agreement with quantum chemical calculations is obtained for the components of the polarizability perpendicular to the chain, but the re sults are less satisfying for the component along the chain. An inherent de ficiency of using atomic capacitancies for large molecules and long chains is discussed. (C) 2001 John Wiley & Sons, Inc.