Application of a Fluctuating Charge Polarization Model to Large Polyaromatic Hydrocarbons and Graphene Nanoflakes

We present a polarization model incorporating coupled fluctuating charges and point inducible dipoles that is able to accurately describe the dipole polarizabilities of small hydrocarbons and, for sufficiently large graphene nanoflakes, reproduce the classical image potential of an infinite conducting sheet. When our fluctuating charge model is applied to the hexagonal carbon nanoflake C-60000 we attain excellent agreement with the image potential and induced charge distribution of a conducting sheet. With the inclusion of inducible dipole terms, the model predicts an image plane of z(im) = 1.3334 a(0), which falls in line with prior estimates for graphene. We consider the case of two charges placed on opposite sides of C-60000 and find that the fluctuating charge model reproduces classical electrostatics once again. By testing opposing and similar signs of the external charges, we conclude that an atomically thin molecule or extended system does not fully screen their interaction.

Automated summary

We propose a polarization model that incorporates fluctuating charges and inducible dipoles to accurately describe dipole polarizabilities of hydrocarbons and reproduce the classical image potential of a conducting sheet. Applying this model to the hexagonal carbon nanoflake C-60000, we obtain excellent agreement with the image potential and induced charge distribution of a conducting sheet. Including inducible dipole terms, the model predicts an image plane of z(im) = 1.3334 a(0), consistent with prior estimates for graphene. We also find that the fluctuating charge model reproduces classical electrostatics for two charges placed on opposite sides of C-60000, indicating that an atomically thin molecule or extended system does not fully screen their interaction.