An electrostatic interaction model for frequency-dependent polarizability:: methodology and applications to hydrocarbons and fullerenes

We present an electrostatic interaction model for the calculation of frequency-dependent electronic polarizability. The model is based on the representation of atoms by an induced electric charge and a dipole moment. The extension of the charge-dipole model to the interaction with oscillating electric fields requires us to account for the kinetics of the free moving charges and of the atomic dipoles. This step is achieved by first relating the oscillations of the atomic charges to the currents that flow through the atomic bonds. Adopting a classical description of this system of charges and dipoles, the time evolution of these quantities is determined from the principle that the action be minimized. As an application of this model, we compute the frequency-dependent molecular polarizability of hydrocarbons with different hybridization. We propose parameters for each chemical group, which provide an excellent agreement with reference data provided by current-density-functional theory. We finally study the frequency-dependent molecular polarizability of fullerenes ranging from C(60) to C(1500).