From VO₂ to V₂O₃: The metal-insulator transition of the Magnéli phase V₆O₁₁

The metal-insulator transition (MIT) of V₆O₁₁ is studied by means of electronic structure calculations using the augmented spherical wave method. The calculations are based on density functional theory and the local density approximation. Changes of the electronic structure at the MIT are discussed in relation to the structural transformations occurring simultaneously. The analysis is based on a unified point of view of the crystal structures of V₆O₁₁, VO₂, and V₂O₃. This allows to group the electronic bands into states behaving similarly to the dioxide or the sesquioxide. While the sesquioxide-like V 3d_yz states show rather weak changes on entering the low-temperature structure, some of the dioxide-like V 3d_x2-_y2 states display splittings and shifts similar to those known from VO₂. The MIT of V₆O₁₁ arises as a combination of changes appearing in both of these compounds. Our results shed new light onto the role of particular electronic states for the MIT of V₂O₃.