@article{31254,
  author       = {{Bocchini, Adriana and Gerstmann, Uwe and Schmidt, Wolf Gero}},
  journal      = {{Phys. Rev. B}},
  pages        = {{205118}},
  publisher    = {{American Physical Society}},
  title        = {{{Oxygen vacancies in KTiOPO_4: Optical absorption from hybrid DFT}}},
  doi          = {{10.1103/PhysRevB.105.205118}},
  volume       = {{105}},
  year         = {{2022}},
}

@article{44088,
  abstract     = {{Hole polarons and defect-bound exciton polarons in lithium niobate are investigated by means of density-functional theory, where the localization of the holes is achieved by applying the +U approach to the oxygen 2p orbitals. We find three principal configurations of hole polarons: (i) self-trapped holes localized at displaced regular oxygen atoms and (ii) two other configurations bound to a lithium vacancy either at a threefold coordinated oxygen atom above or at a two-fold coordinated oxygen atom below the defect. The latter is the most stable and is in excellent quantitative agreement with measured g factors from electron paramagnetic resonance. Due to the absence of mid-gap states, none of these hole polarons can explain the broad optical absorption centered between 2.5 and 2.8 eV that is observed in transient absorption spectroscopy, but such states appear if a free electron polaron is trapped at the same lithium vacancy as the bound hole polaron, resulting in an exciton polaron. The dielectric function calculated by solving the Bethe–Salpeter equation indeed yields an optical peak at 2.6 eV in agreement with the two-photon experiments. The coexistence of hole and exciton polarons, which are simultaneously created in optical excitations, thus satisfactorily explains the reported experimental data.}},
  author       = {{Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}},
  issn         = {{2073-4352}},
  journal      = {{Crystals}},
  number       = {{11}},
  publisher    = {{MDPI AG}},
  title        = {{{A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate}}},
  doi          = {{10.3390/cryst12111586}},
  volume       = {{12}},
  year         = {{2022}},
}

@article{37713,
  author       = {{Murzakhanov, Fadis F. and Mamin, Georgy Vladimirovich and Orlinskii, Sergei Borisovich and Gerstmann, Uwe and Schmidt, Wolf Gero and Biktagirov, Timur and Aharonovich, Igor and Gottscholl, Andreas and Sperlich, Andreas and Dyakonov, Vladimir and Soltamov, Victor A.}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  keywords     = {{Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}},
  number       = {{7}},
  pages        = {{2718--2724}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Electron–Nuclear Coherent Coupling and Nuclear Spin Readout through Optically Polarized V<sub>B</sub><sup>–</sup> Spin States in hBN}}},
  doi          = {{10.1021/acs.nanolett.1c04610}},
  volume       = {{22}},
  year         = {{2022}},
}

@inbook{30288,
  abstract     = {{Lithium niobate (LiNbO3), a material frequently used in optical applications, hosts different kinds of polarons that significantly affect many of its physical properties. In this study, a variety of electron polarons, namely free, bound, and bipolarons, are analyzed using first-principles calculations. We perform a full structural optimization based on density-functional theory for selected intrinsic defects with special attention to the role of symmetry-breaking distortions that lower the total energy. The cations hosting the various polarons relax to a different degree, with a larger relaxation corresponding to a larger gap between the defect level and the conduction-band edge. The projected density of states reveals that the polaron states are formerly empty Nb 4d states lowered into the band gap. Optical absorption spectra are derived within the independent-particle approximation, corrected by the GW approximation that yields a wider band gap and by including excitonic effects within the Bethe-Salpeter equation. Comparing the calculated spectra with the density of states, we find that the defect peak observed in the optical absorption stems from transitions between the defect level and a continuum of empty Nb 4d states. Signatures of polarons are further analyzed in the reflectivity and other experimentally measurable optical coefficients.}},
  author       = {{Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}},
  booktitle    = {{New Trends in Lithium Niobate: From Bulk to Nanocrystals}},
  editor       = {{Corradi, Gábor and Kovács, László}},
  isbn         = {{978-3-0365-3340-7}},
  pages        = {{231--248}},
  publisher    = {{MDPI}},
  title        = {{{Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response}}},
  doi          = {{10.3390/books978-3-0365-3339-1}},
  year         = {{2022}},
}