Volume 58, Number 6, June 2002
|Page(s)||851 - 856|
|Section||Condensed matter: structure, mechanical and thermal properties|
|Published online||01 June 2002|
The metal-insulator transition of : An embedded Peierls instability
Institut für Physik, Universität Augsburg -
86135 Augsburg, Germany
Corresponding author: email@example.com
Accepted: 2 April 2002
Results of first-principles augmented spherical-wave electronic-structure calculations for niobium dioxide are presented. Both metallic rutile and insulating low-temperature , which crystallizes in a distorted rutile structure, are correctly described within density functional theory and the local density approximation. Metallic conductivity is carried by metal orbitals, which fall into the one-dimensional band and the isotropically dispersing bands. Hybridization of both types of bands is almost negligible outside narrow rods along the line X-R. In the low-temperature phase splitting of the band due to metal-metal dimerization as well as upshift of the bands due to increased p - d overlap remove the Fermi surface and open an optical band gap of about 0.1 eV. The metal-insulator transition arises as a Peierls instability of the band in an embedding background of electrons. This basic mechanism should also apply to , where, however, electronic correlations are expected to play a greater role due to stronger localization of the 3d electrons.
PACS: 71.20.-b – Electron density of states and band structure of crystalline solids / 71.30.+h – Metal-insulator transitions and other electronic transitions / 72.15.Nj – Collective modes (e.g., in one-dimensional conductors)
© EDP Sciences, 2002
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