DFT / TDDFT Investigation of Excited‐State Charge Transfer and Spectroscopic Properties in Nd@ C 82 Endohedral Metallofullerenes

ABSTRACT Endohedral metallofullerenes are unique carbon nanostructures in which metal atoms are encapsulated inside fullerene cages. In this work, two representative Nd@C 82 isomers, Nd@ C s (6)‐C 82 and Nd@ C 2v (9)‐C 82 , were systematically investigated using density functional theory and time‐dependent density functional theory to understand the effects of cage isomerism and Nd encapsulation on their electronic and spectroscopic properties. Spin‐state calculations reveal that the quintet state is the lowest‐energy electronic state for both Nd@C 82 isomers. The results show that Nd encapsulation regulates the frontier electronic structures and excited‐state transition behaviors of the C 82 frameworks. Optical analyses demonstrate that the absorption and nonlinear optical responses are mainly dominated by the fullerene cages, accompanied by moderate Nd–cage electronic coupling. ECD analyses further indicate that Nd encapsulation modulates chiroptical responses through electronic transition characteristics rather than introducing intrinsic chirality into the C 82 cages. Raman analyses reveal that the vibrational properties are primarily governed by the carbon frameworks, with only limited low‐frequency modes involving noticeable Nd motion. This work provides molecular‐level insights into the relationship between cage structures, metal–cage interactions, and spectroscopic properties in rare‐earth endohedral metallofullerenes.