Abstract
exhibits a structural phase transition at K. Utilizing the density functional theory, we have simulated optical spectra above and below . Simulated optical absorption spectra for a specific (5X) structure show great agreement with experimental data below , which provides the structural identification of at low temperature. Comparison between experimental and calculated optical spectra also indicates that the Ir-Ir dimer formation governs the optical transition over the wide energy window of the low frequency part. The analysis of Fermi surfaces and band dispersions supports the effects of dimerization on the optical spectra at the low frequency region. The conductivity calculation based on the Boltzmann transport theory within the constant relaxation time approximation reveals that the dimensional reduction as well as the change of conducting plane takes place during the structural transition of .
- Received 11 August 2014
- Revised 21 October 2014
DOI:https://doi.org/10.1103/PhysRevB.90.195136
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