Progress toward a one-electron model for the non-valence correlation-bound anions of polycyclic aromatic hydrocarbons

Abstract

A one-electron model Hamiltonian is used to characterize the non-valence correlation-bound (NVCB) anions of hexagonal polycyclic aromatic hydrocarbons (PAHs) (n = 3–7). The model incorporates atomic electrostatic moments up to the quadrupole, coupled inducible charges and dipoles, and atom-centered repulsive Gaussians to describe the interaction between the excess electron and PAH. These model components are parameterized on and validated against all-electron calculations. Good agreement is found between the static dipole polarizabilities obtained from the model and those from PBE0 density functional theory and second-order Møller–Plesset perturbation theory calculations. In the model, charge flow dominates the in-plane polarizability of PAHs larger than C54H18, yielding an approximately quadratic scaling of the mean polarizabilty with the number of carbon atoms. Inclusion of electrostatic interactions decreases the electron binding energies for the largest PAHs considered by about 20% and shift charge distribution from above and below the plane of the ring system toward the periphery. Analysis of the electrostatic and polarization interactions provides insight into qualitative trends in the electron binding energy and the charge distribution of the lowest energy NVCB anion.