@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}},
}

@article{29748,
  author       = {{Slawig, Diana and Gruschwitz, Markus and Gerstmann, Uwe and Rauls, Eva and Tegenkamp, Christoph}},
  issn         = {{1932-7447}},
  journal      = {{The Journal of Physical Chemistry C}},
  keywords     = {{Surfaces, Coatings and Films, Physical and Theoretical Chemistry, General Energy, Electronic, Optical and Magnetic Materials}},
  number       = {{36}},
  pages        = {{20087--20093}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Adsorption and Reaction of PbPc on Hydrogenated Epitaxial Graphene}}},
  doi          = {{10.1021/acs.jpcc.1c06320}},
  volume       = {{125}},
  year         = {{2021}},
}

@article{21946,
  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}},
  issn         = {{2073-4352}},
  journal      = {{Crystals}},
  pages        = {{542}},
  publisher    = {{MDPI}},
  title        = {{{Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response}}},
  doi          = {{10.3390/cryst11050542}},
  volume       = {{11}},
  year         = {{2021}},
}

@article{22881,
  author       = {{Nguyen, T. T. Nhung and Sollfrank, T. and Tegenkamp, C. and Rauls, E. and Gerstmann, Uwe}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  pages        = {{L201408}},
  title        = {{{Impact of screening and relaxation on weakly coupled two-dimensional heterostructures}}},
  doi          = {{10.1103/physrevb.103.l201408}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{22310,
  author       = {{Neufeld, Sergej and Bocchini, Adriana and Schmidt, Wolf Gero}},
  issn         = {{2475-9953}},
  journal      = {{Physical Review Materials}},
  title        = {{{Potassium titanyl phosphate Z- and Y-cut surfaces from density-functional theory}}},
  doi          = {{10.1103/physrevmaterials.5.064407}},
  year         = {{2021}},
}

@article{22008,
  author       = {{Plaickner, Julian and Speiser, Eugen and Braun, Christian and Schmidt, Wolf Gero and Esser, Norbert and Sanna, Simone}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  title        = {{{Surface localized phonon modes at the Si(553)-Au nanowire system}}},
  doi          = {{10.1103/physrevb.103.115441}},
  year         = {{2021}},
}

@article{40244,
  author       = {{Meier, Lukas and Schmidt, Wolf Gero}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  keywords     = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}},
  number       = {{1}},
  publisher    = {{Wiley}},
  title        = {{{GaInP/AlInP(001) Interfaces from Density Functional Theory}}},
  doi          = {{10.1002/pssb.202100462}},
  volume       = {{259}},
  year         = {{2021}},
}

@article{22009,
  author       = {{Ruiz Alvarado, Isaac Azahel and Karmo, Marsel and Runge, Erich and Schmidt, Wolf Gero}},
  issn         = {{2470-1343}},
  journal      = {{ACS Omega}},
  pages        = {{6297--6304}},
  title        = {{{InP and AlInP(001)(2 × 4) Surface Oxidation from Density Functional Theory}}},
  doi          = {{10.1021/acsomega.0c06019}},
  year         = {{2021}},
}

@article{24975,
  author       = {{Franz, Martin and Chandola, Sandhya and Koy, Maximilian and Zielinski, Robert and Aldahhak, Hazem and Das, Mowpriya and Freitag, Matthias and Gerstmann, Uwe and Liebig, Denise and Hoffmann, Adrian Karl and Rosin, Maximilian and Schmidt, Wolf Gero and Hogan, Conor and Glorius, Frank and Esser, Norbert and Dähne, Mario}},
  issn         = {{1755-4330}},
  journal      = {{Nature Chemistry}},
  pages        = {{828--835}},
  title        = {{{Controlled growth of ordered monolayers of N-heterocyclic carbenes on silicon}}},
  doi          = {{10.1038/s41557-021-00721-2}},
  year         = {{2021}},
}

@article{23418,
  abstract     = {{Density-functional theory within a Berry-phase formulation of the dynamical polarization is used to determine the second-order susceptibility χ(2) of lithium niobate (LiNbO3). Defect trapped polarons and bipolarons are found to strongly enhance the nonlinear susceptibility of the material, in particular if localized at NbV–VLi defect pairs. This is essentially a consequence of the polaronic excitation resulting in relaxation-induced gap states. The occupation of these levels leads to strongly enhanced χ(2) coefficients and allows for the spatial and transient modification of the second-harmonic generation of macroscopic samples.}},
  author       = {{Kozub, Agnieszka L. and Schindlmayr, Arno and Gerstmann, Uwe and Schmidt, Wolf Gero}},
  issn         = {{2469-9969}},
  journal      = {{Physical Review B}},
  pages        = {{174110}},
  publisher    = {{American Physical Society}},
  title        = {{{Polaronic enhancement of second-harmonic generation in lithium niobate}}},
  doi          = {{10.1103/PhysRevB.104.174110}},
  volume       = {{104}},
  year         = {{2021}},
}

@article{40250,
  author       = {{Jain, Mitisha and Gerstmann, Uwe and Schmidt, Wolf Gero and Aldahhak, Hazem}},
  issn         = {{0192-8651}},
  journal      = {{Journal of Computational Chemistry}},
  keywords     = {{Computational Mathematics, General Chemistry}},
  number       = {{6}},
  pages        = {{413--420}},
  publisher    = {{Wiley}},
  title        = {{{Adatom mediated adsorption of            <scp>N‐heterocyclic</scp>            carbenes on Cu(111) and Au(111)}}},
  doi          = {{10.1002/jcc.26801}},
  volume       = {{43}},
  year         = {{2021}},
}

@article{29747,
  author       = {{Jurgen von Bardeleben, Hans and Cantin, Jean-Louis and Gerstmann, Uwe and Schmidt, Wolf Gero and Biktagirov, Timur}},
  issn         = {{1530-6984}},
  journal      = {{Nano Letters}},
  keywords     = {{Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}},
  number       = {{19}},
  pages        = {{8119--8125}},
  publisher    = {{American Chemical Society (ACS)}},
  title        = {{{Spin Polarization, Electron–Phonon Coupling, and Zero-Phonon Line of the NV Center in 3C-SiC}}},
  doi          = {{10.1021/acs.nanolett.1c02564}},
  volume       = {{21}},
  year         = {{2021}},
}

@article{29749,
  author       = {{Murzakhanov, F. F. and Yavkin, B. V. and Mamin, G. V. and Orlinskii, S. B. and von Bardeleben, H. J. and Biktagirov, Timur and Gerstmann, Uwe and Soltamov, V. A.}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  pages        = {{245203}},
  publisher    = {{American Physical Society (APS)}},
  title        = {{{Hyperfine and nuclear quadrupole splitting of the NV− ground state in 4H-SiC}}},
  doi          = {{10.1103/physrevb.103.245203}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{22010,
  author       = {{Aldahhak, Hazem and Hogan, Conor and Lindner, Susi and Appelfeller, Stephan and Eisele, Holger and Schmidt, Wolf Gero and Dähne, Mario and Gerstmann, Uwe and Franz, Martin}},
  issn         = {{2469-9950}},
  journal      = {{Physical Review B}},
  pages        = {{035303}},
  title        = {{{Electronic structure of the Si(111)3×3R30∘−B surface from theory and photoemission spectroscopy}}},
  doi          = {{10.1103/physrevb.103.035303}},
  volume       = {{103}},
  year         = {{2021}},
}

@article{40233,
  author       = {{Meier, Lukas and Braun, Christian and Hannappel, Thomas and Schmidt, Wolf Gero}},
  issn         = {{0370-1972}},
  journal      = {{physica status solidi (b)}},
  keywords     = {{Condensed Matter Physics, Electronic, Optical and Magnetic Materials}},
  number       = {{2}},
  publisher    = {{Wiley}},
  title        = {{{Band Alignment at Ga            <sub>              <i>x</i>            </sub>            In            <sub>              1–              <i>x</i>            </sub>            P/Al            <sub>              <i>y</i>            </sub>            In            <sub>              1–              <i>y</i>            </sub>            P Alloy Interfaces from Hybrid Density Functional Theory Calculations}}},
  doi          = {{10.1002/pssb.202000463}},
  volume       = {{258}},
  year         = {{2020}},
}

@article{17067,
  author       = {{Speiser, Eugen and Esser, Norbert and Halbig, Benedikt and Geurts, Jean and Schmidt, Wolf Gero and Sanna, Simone}},
  issn         = {{0167-5729}},
  journal      = {{Surface Science Reports}},
  number       = {{1}},
  title        = {{{Vibrational Raman spectroscopy on adsorbate-induced low-dimensional surface structures}}},
  doi          = {{10.1016/j.surfrep.2020.100480}},
  volume       = {{75}},
  year         = {{2020}},
}

@article{19190,
  abstract     = {{Polarons in dielectric crystals play a crucial role for applications in integrated electronics and optoelectronics. In this work, we use density-functional theory and Green's function methods to explore the microscopic structure and spectroscopic signatures of electron polarons in lithium niobate (LiNbO3). Total-energy calculations and the comparison of calculated electron paramagnetic resonance data with available measurements reveal the formation of bound 
polarons at Nb_Li antisite defects with a quasi-Jahn-Teller distorted, tilted configuration. The defect-formation energies further indicate that (bi)polarons may form not only at 
Nb_Li antisites but also at structures where the antisite Nb atom moves into a neighboring empty oxygen octahedron. Based on these structure models, and on the calculated charge-transition levels and potential-energy barriers, we propose two mechanisms for the optical and thermal splitting of bipolarons, which provide a natural explanation for the reported two-path recombination of bipolarons. Optical-response calculations based on the Bethe-Salpeter equation, in combination with available experimental data and new measurements of the optical absorption spectrum, further corroborate the geometries proposed here for free and defect-bound (bi)polarons.}},
  author       = {{Schmidt, Falko and Kozub, Agnieszka L. and Biktagirov, Timur and Eigner, Christof and Silberhorn, Christine and Schindlmayr, Arno and Schmidt, Wolf Gero and Gerstmann, Uwe}},
  issn         = {{2643-1564}},
  journal      = {{Physical Review Research}},
  number       = {{4}},
  publisher    = {{American Physical Society}},
  title        = {{{Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations}}},
  doi          = {{10.1103/PhysRevResearch.2.043002}},
  volume       = {{2}},
  year         = {{2020}},
}

@article{17066,
  author       = {{Aldahhak, Hazem and Powroźnik, Paulina and Pander, Piotr and Jakubik, Wiesław and Dias, Fernando B. and Schmidt, Wolf Gero and Gerstmann, Uwe and Krzywiecki, Maciej}},
  issn         = {{1932-7447}},
  journal      = {{The Journal of Physical Chemistry C}},
  number       = {{124}},
  pages        = {{6090--6102}},
  title        = {{{Toward Efficient Toxic-Gas Detectors: Exploring Molecular Interactions of Sarin and Dimethyl Methylphosphonate with Metal-Centered Phthalocyanine Structures}}},
  doi          = {{10.1021/acs.jpcc.9b11116}},
  year         = {{2020}},
}