Molecular-Orbital Degeneracy Lifting and Suppression of a Flat-Band Metal in a Tetrahedral Cluster System NbSeI
The study investigates how two mechanisms—molecular orbital ordering and noncooperative Jahn-Teller distortion—lift electronic degeneracy in NbSeI, causing it to be a nonmagnetic insulator across all temperatures below room temperature. This research shows that these local distortions are crucial for stabilizing insulating states, contradicting predictions of a flat-band metal.