TDDFT study on the second-order nonlinear optical properties of a series of mono- and di-nuclear [60]fullerene complexes

Time-dependent density functional theory (TDDFT) was employed to study second-order nonlinear optical (NLO) properties of transition metal fullerene complexes with a face to face model. The results show that the ruthenium species possesses the larger second-order NLO response than that of the iron species. Chemical modifications of the fullerene by carbon-carbon bond scission can tune charge transfer character in these complexes, and increase the static first hyperpolarizability. The electronic structure analysis and TDDFT calculations show that the open-cage complex in the ruthenium species possesses low-lying and strong charge transfer transitions, and thus give the largest second-order NLO response.