Excitonic Effects on the Linear and Nonlinear Optical Properties of Solid C60 Fullerene, Insights from Many-Body First-Principles Calculations

Abstract

We perform the many-body Bethe-Salpeter equation eigenstates based sum-over-states calculations for the linear and nonlinear optical properties of solid C 60 fullerene. Excitonic and local field effects are included in the calculations. We calculate the one-photon absorption (OPA), third harmonic generation (THG), degenerate four-wave mixing (DFWM), and electric-field-induced second harmonic generation (ESHG) spectra of solid C 60 fullerene. The overall agreement between the theoretical and experimental results is good for all calculated spectra. The OPA spectrum shows that the solid C 60 fullerene has a large excitonic binding energy of 0.35 eV. The position and intensity of spectral peaks are modified significantly. By tracing the sum-over-states progress, we determine the type of nonlinear polarization resonances for the characteristic peaks of the THG process, which may clear up a discrepancy in two experimental results. The calculated DFWM spectrum is in excellent agreement with the available experimental results in terms of line shape and peak positions, and thus the two-photon absorption peaks can be well understood on the basis of the excitonic states of solid C 60 fullerene. The dynamic ESHG spectrum is given as a reference for the future experiment.