A charge-dipole model for the static polarizability of nanostructures including aliphatic, olephinic, and aromatic...

We present an electrostatic interaction model for the calculation of the static electronic polarization of hydrocarbons. In previous work, models have often been presented for one single type of hydrocarbons. Here, we discuss the different requirements for a model to describe aliphatic, olephinic, and aromatic systems. The model is based on the representation of the carbon and hydrogen atoms by induced electric charges and dipoles, where the actual values of the charges and dipoles are those that minimize the electrochemical energy of the molecule. The electrostatic interactions are described in terms of normalized propagators, which improves both the consistency and the numerical stability of the technique. For the calibration of our model, we sought at reproducing the molecular polarizabilities obtained by current density functional theory for a set of 48 reference structures. We propose parameters for each type of hydrocarbon, which provide an excellent agreement with the reference data (relative error on the mean molecular polarizabilities of 0.5, 1.4, and 1.9% for alkanes, alkenes, and aromatic molecules, respectively). We also propose parameters based on the local environment of each atom, which are better suited for the description of more complex molecules. We finally study the polarizability of fullerenes and small hydrogen-terminated (5,5) carbon nanotubes.