Structural Transition of Li₂RuO₃Induced by Molecular-Orbit Formation

Abstract

A pseudo honeycomb system Li2RuO3 exhibits a second-order-like transition at\ntemperature T=Tc=540 K to a low-T nonmagnetic phase with a significant lattice\ndistortion forming Ru-Ru pairs. For this system, we have calculated the band\nstructure, using the generalized gradient approximation (GGA) in both the high-\nand low- T phases, and found that the results of the calculation can naturally\nexplain the insulating behavior observed in the low-T phase. The detailed\ncharacters of the Ru 4d t2g bands obtained by the tight-binding fit to the\ncalculated dispersion curves show clear evidence that the structural transition\nis driven by the formation of the Ru-Ru molecular-orbits, as proposed in our\nprevious experimental studies.\n