Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory
M. Friedrich, W.G. Schmidt, A. Schindlmayr, S. Sanna, Physical Review Materials 1 (2017).
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The optical properties of congruent lithium niobate are analyzed from first principles. The dielectric function of the material is calculated within time-dependent density-functional theory. The effects of isolated intrinsic defects and defect pairs, including the NbLi4+ antisite and the NbLi4+−NbNb4+ pair, commonly addressed as a bound polaron and bipolaron, respectively, are discussed in detail. In addition, we present further possible realizations of polaronic and bipolaronic systems. The absorption feature around 1.64 eV, ascribed to small bound polarons [O. F. Schirmer et al., J. Phys.: Condens. Matter 21, 123201 (2009)], is nicely reproduced within these models. Among the investigated defects, we find that the presence of bipolarons at bound interstitial-vacancy pairs NbV−VLi can best explain the experimentally observed broad absorption band at 2.5 eV. Our results provide a microscopic model for the observed optical spectra and suggest that, besides NbLi antisites and Nb and Li vacancies, Nb interstitials are also formed in congruent lithium-niobate samples.
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Journal Title
Physical Review Materials
Volume
1
Issue
5
Article Number
054406
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Friedrich M, Schmidt WG, Schindlmayr A, Sanna S. Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory. Physical Review Materials. 2017;1(5). doi:10.1103/PhysRevMaterials.1.054406
Friedrich, M., Schmidt, W. G., Schindlmayr, A., & Sanna, S. (2017). Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory. Physical Review Materials, 1(5). https://doi.org/10.1103/PhysRevMaterials.1.054406
@article{Friedrich_Schmidt_Schindlmayr_Sanna_2017, title={Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory}, volume={1}, DOI={10.1103/PhysRevMaterials.1.054406}, number={5054406}, journal={Physical Review Materials}, publisher={American Physical Society}, author={Friedrich, Michael and Schmidt, Wolf Gero and Schindlmayr, Arno and Sanna, Simone}, year={2017} }
Friedrich, Michael, Wolf Gero Schmidt, Arno Schindlmayr, and Simone Sanna. “Polaron Optical Absorption in Congruent Lithium Niobate from Time-Dependent Density-Functional Theory.” Physical Review Materials 1, no. 5 (2017). https://doi.org/10.1103/PhysRevMaterials.1.054406.
M. Friedrich, W. G. Schmidt, A. Schindlmayr, and S. Sanna, “Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory,” Physical Review Materials, vol. 1, no. 5, 2017.
Friedrich, Michael, et al. “Polaron Optical Absorption in Congruent Lithium Niobate from Time-Dependent Density-Functional Theory.” Physical Review Materials, vol. 1, no. 5, 054406, American Physical Society, 2017, doi:10.1103/PhysRevMaterials.1.054406.
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