Ultrafast relaxation of photoexcited C₆₀: a comparison among DFT models

Studies of the relaxation dynamics of photoexcited electrons in fullerene materials have applications in organic photovoltaics and medical photothermal therapy. In this work, we use an approach of electron-phonon coupled nonadiabatic molecular dynamics [1], based on density functional theory (DFT) [2-3], to simulate such relaxation process in C₆₀. The methodology relies on a combination of the fewest-switch surface hopping approach and Kohn−Sham single-particle description [2]. We calculate the femtosecond evolution of the population of initial excited states and of various intermediate states. A comparison of results obtained using the PBE, PBE0, and B3LYP exchange-correlation functional, will be presented. The population lifetimes are found to reflect the structure of unoccupied band which may inspire experiments in laser two-photon schemes. [1] M. Madjet et al., Phys. Rev. Lett. 126, 183002, (2021); [2] A V. Akimov and O.V Prezhdo, J. Chem. Theory Comput. 9, 11 (2013); [3] M. Madjet et al. J. Phys. Chem. Lett 8, 18 (2017).