Optical response of metallic and insulating VO2 calculated with the LDA approach
arXiv:cond-mat/0608462 · doi:10.1088/0953-8984/19/34/346225
Abstract
We calculated the optical response of metallic and insulating VO2 using the LDA approach. The band structure calculation was based in the full-potential linear-muffin-tin method. The imaginary part of the dielectric function e2(w) is related to the different optical transitions. The Drude tail in the calculation of the metallic phase corresponds to intra-band d-d transitions. The calculation in the insulating phase is characterized by the transitions to the d||* band. The low frequency features, 0.0-5.0 eV, correspond to V 3d-V 3d transitions, whereas the high frequency structures, 5.0-12 eV, are related to O 2p-V 3d transitions. The calculation helps to explain the imaginary part of the dielectric function e2(w), as well as the electron-energy-loss and reflectance spectra. The results reproduce not only the energy position and relative intensity of the features in the spectra, but also the main changes across the metal-insulator transition and the polarization dependence. The main difference is a shift of about 0.6 eV in the calculation of the insulating phase. This discrepancy arises because the LDA calculation underestimates the value of the band gap.
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