Ionization energy and electron affinity of fullerene C60 in the Hubbard model in the static fluctuation approximation

Abstract

Within the Hubbard model, the ionization energy and electron affinity of the icosahedral C60 fullerene are calculated in the static fluctuation approximation. A graphical representation of the chemical potential equation is first obtained. The correlation function, which describes the transitions of {\pi}-electrons from one fullerene site to the nearest site, and the thermodynamic average, which characterizes the probability of detecting two {\pi}-electrons with oppositely oriented spin projections on a single fullerene site, are then calculated. The theoretically obtained values for the ionization energy of 7.57 eV and the electron affinity of 2.67 eV coincide with the experimentally observed values and demonstrate that, during photoionization or another process leading to either the acquisition or loss of a {\pi}-electron, the fullerene responds to external perturbations as a single system of strongly correlated {\pi}-electrons.