ELECTRONIC-STRUCTURE OF RHOMBOHEDRAL TI2O3

The band properties of corundum-phase Ti2O3 have been calculated in th e local-density approximation with the use of the linear augmented-pla ne-wave method. The results consist of low-lying O 2p states and a par tially filled t(2g) complex near E(F) where metallic behaviour origina tes from overlapping a(1g) and e(g)(pi) subbands. Decreasing the c/a r atio (even beyond the observed low-temperature value) reduces but does not eliminate this a(1g)-e(g)(pi) band overlap, thereby precluding a band explanation for the metal-insulator transition that is observed i n this system with no accompanying structural distortion.