Structural, electronic, and optical properties of α, β, and γ-TeO2

First-principles calculations of the structural, electronic, and optical properties of TeO2 polymorphs were performed with the density functional theory plane-wave pseudopotential method. The results reveal that all the three crystalline TeO2 phases are wide-gap semiconductors and the lone electron pairs have contributions near the Fermi energy level. The layer structure of beta-TeO2 leads to the obvious anisotropy of the complex dielectric function. Considering the lattice contribution of dielectric constants, we predict the static dielectric constants of TeO2 polymorphs. For alpha-TeO2, the calculated values of 19.0 for epsilon(1 perpendicular to) and 25.3 for epsilon(1 parallel to) agree well with the experimental value, and the beta- and gamma-phases also belong to the high dielectric constant materials. Besides, a special collective plasma resonance for gamma-TeO2 has been found in lower energy. It corresponds to the small peak in the imaginary part of dielectric function, and reflects the abrupt reduction in the reflectivity spectrum. (C) 2010 American Institute of Physics. [doi:10.1063/1.3406135]