Polarizability and Image Potential States of Large Graphene Nanoflakes

Considerable experimental and theoretical work has been done on the image potential states of graphene. In a many-body treatment these states result from dispersion-type interaction between the excess electron and the electrons of graphene, but in a one-electron treatment these are attributed to the long-range -1/4z image potential. Non-valence correlation-bound (NVCB) anions of molecules and clusters are the finite system analog of image potential states. We have been addressing the evolution of the NVCB anion states of C_6n²H_6n polyaromatic hydrocarbons as well as of hypothetical C_6n² clusters (ignoring the effects of dangling bonds) as a function of n. Key to this effort is the development of a polarization model that includes both point-inducible dipoles and charge-flow polarization. We demonstrate that even for C_6n²H_6n species with over 10000 C atoms, the NVCB anion states a significantly different from the image potential states of graphene due to the electrostatic interactions with the periphery CH bonds. Inclusion charge-flow polarization is essential for the characterization of the NVCB anions of these nanoflake systems.