[{"year":"2025","quality_controlled":"1","issue":"18","title":"Ab initio calculations of spin waves: A review of theoretical approaches and applications","publisher":"MDPI","date_created":"2025-09-15T16:14:59Z","abstract":[{"text":"Spin waves represent an important class of low-energy excitations in magnetic solids, which influence the thermodynamic properties and play a major role in technical applications, such as spintronics or magnetic data storage. Despite the enormous advances of ab initio simulations in materials science, quantitative calculations of spin-wave spectra still pose a significant challenge, because the collective nature of the spin dynamics requires an accurate treatment of the Coulomb interaction between the electrons. As a consequence, simple lattice models like the Heisenberg Hamiltonian are still widespread in practical investigations, but modern techniques like time-dependent density-functional theory or many-body perturbation theory also open a route to material-specific spin-wave calculations from first principles. Although both are in principle exact, actual implementations necessarily employ approximations for electronic exchange and correlation as well as additional numerical simplifications. In this review, we recapitulate the theoretical foundations of ab initio spin-wave calculations and analyze the common approximations that underlie present implementations. In addition, we survey the available results for spin-wave dispersions of various magnetic materials and compare the performance of different computational approaches. In this way, we provide an overview of the present state of the art and identify directions for further developments.","lang":"eng"}],"file":[{"content_type":"application/pdf","creator":"schindlm","file_name":"materials-18-04431.pdf","file_size":611341,"relation":"main_file","date_created":"2025-09-24T07:19:36Z","date_updated":"2025-09-24T07:19:36Z","file_id":"61422","access_level":"open_access","title":"Ab initio calculations of spin waves: A review of theoretical approaches and applications","description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)"}],"publication":"Materials","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["001580599300001"]},"citation":{"apa":"Neugum, M., &#38; Schindlmayr, A. (2025). Ab initio calculations of spin waves: A review of theoretical approaches and applications. <i>Materials</i>, <i>18</i>(18), Article 4431. <a href=\"https://doi.org/10.3390/ma18184431\">https://doi.org/10.3390/ma18184431</a>","short":"M. Neugum, A. Schindlmayr, Materials 18 (2025).","bibtex":"@article{Neugum_Schindlmayr_2025, title={Ab initio calculations of spin waves: A review of theoretical approaches and applications}, volume={18}, DOI={<a href=\"https://doi.org/10.3390/ma18184431\">10.3390/ma18184431</a>}, number={184431}, journal={Materials}, publisher={MDPI}, author={Neugum, Michael and Schindlmayr, Arno}, year={2025} }","mla":"Neugum, Michael, and Arno Schindlmayr. “Ab Initio Calculations of Spin Waves: A Review of Theoretical Approaches and Applications.” <i>Materials</i>, vol. 18, no. 18, 4431, MDPI, 2025, doi:<a href=\"https://doi.org/10.3390/ma18184431\">10.3390/ma18184431</a>.","ama":"Neugum M, Schindlmayr A. Ab initio calculations of spin waves: A review of theoretical approaches and applications. <i>Materials</i>. 2025;18(18). doi:<a href=\"https://doi.org/10.3390/ma18184431\">10.3390/ma18184431</a>","chicago":"Neugum, Michael, and Arno Schindlmayr. “Ab Initio Calculations of Spin Waves: A Review of Theoretical Approaches and Applications.” <i>Materials</i> 18, no. 18 (2025). <a href=\"https://doi.org/10.3390/ma18184431\">https://doi.org/10.3390/ma18184431</a>.","ieee":"M. Neugum and A. Schindlmayr, “Ab initio calculations of spin waves: A review of theoretical approaches and applications,” <i>Materials</i>, vol. 18, no. 18, Art. no. 4431, 2025, doi: <a href=\"https://doi.org/10.3390/ma18184431\">10.3390/ma18184431</a>."},"intvolume":"        18","publication_status":"published","publication_identifier":{"eissn":["1996-1944"]},"has_accepted_license":"1","doi":"10.3390/ma18184431","oa":"1","date_updated":"2025-10-10T07:31:23Z","author":[{"first_name":"Michael","full_name":"Neugum, Michael","id":"80813","last_name":"Neugum"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458"}],"volume":18,"status":"public","type":"journal_article","isi":"1","article_type":"review","article_number":"4431","file_date_updated":"2025-09-24T07:19:36Z","_id":"61279","user_id":"458","department":[{"_id":"296"},{"_id":"15"},{"_id":"170"},{"_id":"35"},{"_id":"230"}]},{"quality_controlled":"1","issue":"3","year":"2025","publisher":"MDPI","date_created":"2025-08-20T09:46:13Z","title":"Generalized Miller formulae for quantum anharmonic oscillators","publication":"Dynamics","abstract":[{"text":"Miller's rule originated as an empirical relation between the nonlinear and linear optical coefficients of materials. It is now accepted as a useful tool for guiding experiments and computational materials discovery, but its theoretical foundation had long been limited to a derivation for the classical Lorentz model with a weak anharmonic perturbation. Recently, we developed a mathematical framework which enabled us to prove that Miller's rule is equally valid for quantum anharmonic oscillators, despite different dynamics due to zero-point fluctuations and further quantum-mechanical effects. However, our previous derivation applied only to one-dimensional oscillators and to the special case of second- and third-harmonic generation in a monochromatic electric field. Here we extend the proof to three-dimensional quantum anharmonic oscillators and also treat all orders of the nonlinear response to an arbitrary multi-frequency field. This makes the results applicable to a much larger range of physical systems and nonlinear optical processes. The obtained generalized Miller formulae rigorously express all tensor elements of the frequency-dependent nonlinear susceptibilities in terms of the linear susceptibility and thus allow a computationally inexpensive quantitative prediction of arbitrary parametric frequency-mixing processes from a small initial dataset.","lang":"eng"}],"file":[{"description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","file_size":375897,"title":"Generalized Miller formulae for quantum anharmonic oscillators","access_level":"open_access","file_id":"61056","file_name":"dynamics-05-00034.pdf","date_updated":"2025-08-28T12:27:05Z","date_created":"2025-08-28T12:23:26Z","creator":"schindlm","relation":"main_file","content_type":"application/pdf"}],"external_id":{"isi":["001581270200001"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["2673-8716"]},"citation":{"short":"M.T. Meyer, A. Schindlmayr, Dynamics 5 (2025).","mla":"Meyer, Maximilian Tim, and Arno Schindlmayr. “Generalized Miller Formulae for Quantum Anharmonic Oscillators.” <i>Dynamics</i>, vol. 5, no. 3, 34, MDPI, 2025, doi:<a href=\"https://doi.org/10.3390/dynamics5030034\">10.3390/dynamics5030034</a>.","bibtex":"@article{Meyer_Schindlmayr_2025, title={Generalized Miller formulae for quantum anharmonic oscillators}, volume={5}, DOI={<a href=\"https://doi.org/10.3390/dynamics5030034\">10.3390/dynamics5030034</a>}, number={334}, journal={Dynamics}, publisher={MDPI}, author={Meyer, Maximilian Tim and Schindlmayr, Arno}, year={2025} }","apa":"Meyer, M. T., &#38; Schindlmayr, A. (2025). Generalized Miller formulae for quantum anharmonic oscillators. <i>Dynamics</i>, <i>5</i>(3), Article 34. <a href=\"https://doi.org/10.3390/dynamics5030034\">https://doi.org/10.3390/dynamics5030034</a>","ama":"Meyer MT, Schindlmayr A. Generalized Miller formulae for quantum anharmonic oscillators. <i>Dynamics</i>. 2025;5(3). doi:<a href=\"https://doi.org/10.3390/dynamics5030034\">10.3390/dynamics5030034</a>","chicago":"Meyer, Maximilian Tim, and Arno Schindlmayr. “Generalized Miller Formulae for Quantum Anharmonic Oscillators.” <i>Dynamics</i> 5, no. 3 (2025). <a href=\"https://doi.org/10.3390/dynamics5030034\">https://doi.org/10.3390/dynamics5030034</a>.","ieee":"M. T. Meyer and A. Schindlmayr, “Generalized Miller formulae for quantum anharmonic oscillators,” <i>Dynamics</i>, vol. 5, no. 3, Art. no. 34, 2025, doi: <a href=\"https://doi.org/10.3390/dynamics5030034\">10.3390/dynamics5030034</a>."},"intvolume":"         5","date_updated":"2025-10-10T07:29:36Z","oa":"1","author":[{"full_name":"Meyer, Maximilian Tim","id":"77895","orcid":"0009-0003-4899-0920","last_name":"Meyer","first_name":"Maximilian Tim"},{"orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458","first_name":"Arno"}],"volume":5,"doi":"10.3390/dynamics5030034","type":"journal_article","status":"public","_id":"60959","user_id":"458","department":[{"_id":"296"},{"_id":"230"},{"_id":"15"},{"_id":"170"},{"_id":"35"}],"article_number":"34","isi":"1","article_type":"original","file_date_updated":"2025-08-28T12:27:05Z"},{"file":[{"content_type":"application/pdf","relation":"main_file","date_updated":"2024-04-04T09:24:22Z","date_created":"2024-04-04T09:24:22Z","creator":"schindlm","file_size":358155,"description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"Derivation of Miller's rule for the nonlinear optical susceptibility of a quantum anharmonic oscillator","access_level":"open_access","file_name":"Meyer_2024_J._Phys._B _At._Mol._Opt._Phys._57_095001.pdf","file_id":"53204"}],"abstract":[{"text":"Miller's rule is an empirical relation between the nonlinear and linear optical coefficients that applies to a large class of materials but has only been rigorously derived for the classical Lorentz model with a weak anharmonic perturbation. In this work, we extend the proof and present a detailed derivation of Miller's rule for an equivalent quantum-mechanical anharmonic oscillator. For this purpose, the classical concept of velocity-dependent damping inherent to the Lorentz model is replaced by an adiabatic switch-on of the external electric field, which allows a unified treatment of the classical and quantum-mechanical systems using identical potentials and fields. Although the dynamics of the resulting charge oscillations, and hence the induced polarizations, deviate due to the finite zero-point motion in the quantum-mechanical framework, we find that Miller's rule is nevertheless identical in both cases up to terms of first order in the anharmonicity. With a view to practical applications, especially in the context of ab initio calculations for the optical response where adiabatically switched-on fields are widely assumed, we demonstrate that a correct treatment of finite broadening parameters is essential to avoid spurious errors that may falsely suggest a violation of Miller's rule, and we illustrate this point by means of a numerical example.","lang":"eng"}],"publication":"Journal of Physics B: Atomic, Molecular and Optical Physics","language":[{"iso":"eng"}],"ddc":["530"],"external_id":{"isi":["001196678300001"]},"year":"2024","issue":"9","quality_controlled":"1","title":"Derivation of Miller's rule for the nonlinear optical susceptibility of a quantum anharmonic oscillator","date_created":"2024-03-22T08:44:39Z","publisher":"IOP Publishing","status":"public","type":"journal_article","file_date_updated":"2024-04-04T09:24:22Z","article_type":"original","article_number":"095001","isi":"1","user_id":"458","department":[{"_id":"296"},{"_id":"230"},{"_id":"15"},{"_id":"170"},{"_id":"35"}],"_id":"52723","citation":{"chicago":"Meyer, Maximilian Tim, and Arno Schindlmayr. “Derivation of Miller’s Rule for the Nonlinear Optical Susceptibility of a Quantum Anharmonic Oscillator.” <i>Journal of Physics B: Atomic, Molecular and Optical Physics</i> 57, no. 9 (2024). <a href=\"https://doi.org/10.1088/1361-6455/ad369c\">https://doi.org/10.1088/1361-6455/ad369c</a>.","ieee":"M. T. Meyer and A. Schindlmayr, “Derivation of Miller’s rule for the nonlinear optical susceptibility of a quantum anharmonic oscillator,” <i>Journal of Physics B: Atomic, Molecular and Optical Physics</i>, vol. 57, no. 9, Art. no. 095001, 2024, doi: <a href=\"https://doi.org/10.1088/1361-6455/ad369c\">10.1088/1361-6455/ad369c</a>.","ama":"Meyer MT, Schindlmayr A. Derivation of Miller’s rule for the nonlinear optical susceptibility of a quantum anharmonic oscillator. <i>Journal of Physics B: Atomic, Molecular and Optical Physics</i>. 2024;57(9). doi:<a href=\"https://doi.org/10.1088/1361-6455/ad369c\">10.1088/1361-6455/ad369c</a>","apa":"Meyer, M. T., &#38; Schindlmayr, A. (2024). Derivation of Miller’s rule for the nonlinear optical susceptibility of a quantum anharmonic oscillator. <i>Journal of Physics B: Atomic, Molecular and Optical Physics</i>, <i>57</i>(9), Article 095001. <a href=\"https://doi.org/10.1088/1361-6455/ad369c\">https://doi.org/10.1088/1361-6455/ad369c</a>","mla":"Meyer, Maximilian Tim, and Arno Schindlmayr. “Derivation of Miller’s Rule for the Nonlinear Optical Susceptibility of a Quantum Anharmonic Oscillator.” <i>Journal of Physics B: Atomic, Molecular and Optical Physics</i>, vol. 57, no. 9, 095001, IOP Publishing, 2024, doi:<a href=\"https://doi.org/10.1088/1361-6455/ad369c\">10.1088/1361-6455/ad369c</a>.","short":"M.T. Meyer, A. Schindlmayr, Journal of Physics B: Atomic, Molecular and Optical Physics 57 (2024).","bibtex":"@article{Meyer_Schindlmayr_2024, title={Derivation of Miller’s rule for the nonlinear optical susceptibility of a quantum anharmonic oscillator}, volume={57}, DOI={<a href=\"https://doi.org/10.1088/1361-6455/ad369c\">10.1088/1361-6455/ad369c</a>}, number={9095001}, journal={Journal of Physics B: Atomic, Molecular and Optical Physics}, publisher={IOP Publishing}, author={Meyer, Maximilian Tim and Schindlmayr, Arno}, year={2024} }"},"intvolume":"        57","publication_status":"published","has_accepted_license":"1","publication_identifier":{"issn":["0953-4075"],"eissn":["1361-6455"]},"doi":"10.1088/1361-6455/ad369c","author":[{"id":"77895","full_name":"Meyer, Maximilian Tim","last_name":"Meyer","orcid":"0009-0003-4899-0920","first_name":"Maximilian Tim"},{"first_name":"Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","id":"458","full_name":"Schindlmayr, Arno"}],"volume":57,"date_updated":"2024-04-13T11:20:56Z","oa":"1"},{"has_accepted_license":"1","publication_identifier":{"eissn":["2515-7639"]},"publication_status":"published","intvolume":"         5","citation":{"ieee":"S. Neufeld, A. Schindlmayr, and W. G. Schmidt, “Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4,” <i>Journal of Physics: Materials</i>, vol. 5, no. 1, Art. no. 015002, 2022, doi: <a href=\"https://doi.org/10.1088/2515-7639/ac3384\">10.1088/2515-7639/ac3384</a>.","chicago":"Neufeld, Sergej, Arno Schindlmayr, and Wolf Gero Schmidt. “Quasiparticle Energies and Optical Response of RbTiOPO4 and KTiOAsO4.” <i>Journal of Physics: Materials</i> 5, no. 1 (2022). <a href=\"https://doi.org/10.1088/2515-7639/ac3384\">https://doi.org/10.1088/2515-7639/ac3384</a>.","ama":"Neufeld S, Schindlmayr A, Schmidt WG. Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4. <i>Journal of Physics: Materials</i>. 2022;5(1). doi:<a href=\"https://doi.org/10.1088/2515-7639/ac3384\">10.1088/2515-7639/ac3384</a>","short":"S. Neufeld, A. Schindlmayr, W.G. Schmidt, Journal of Physics: Materials 5 (2022).","mla":"Neufeld, Sergej, et al. “Quasiparticle Energies and Optical Response of RbTiOPO4 and KTiOAsO4.” <i>Journal of Physics: Materials</i>, vol. 5, no. 1, 015002, IOP Publishing, 2022, doi:<a href=\"https://doi.org/10.1088/2515-7639/ac3384\">10.1088/2515-7639/ac3384</a>.","bibtex":"@article{Neufeld_Schindlmayr_Schmidt_2022, title={Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4}, volume={5}, DOI={<a href=\"https://doi.org/10.1088/2515-7639/ac3384\">10.1088/2515-7639/ac3384</a>}, number={1015002}, journal={Journal of Physics: Materials}, publisher={IOP Publishing}, author={Neufeld, Sergej and Schindlmayr, Arno and Schmidt, Wolf Gero}, year={2022} }","apa":"Neufeld, S., Schindlmayr, A., &#38; Schmidt, W. G. (2022). Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4. <i>Journal of Physics: Materials</i>, <i>5</i>(1), Article 015002. <a href=\"https://doi.org/10.1088/2515-7639/ac3384\">https://doi.org/10.1088/2515-7639/ac3384</a>"},"oa":"1","date_updated":"2023-04-20T14:01:16Z","volume":5,"author":[{"full_name":"Neufeld, Sergej","id":"23261","last_name":"Neufeld","first_name":"Sergej"},{"first_name":"Arno","id":"458","full_name":"Schindlmayr, Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X"},{"last_name":"Schmidt","orcid":"0000-0002-2717-5076","id":"468","full_name":"Schmidt, Wolf Gero","first_name":"Wolf Gero"}],"doi":"10.1088/2515-7639/ac3384","type":"journal_article","status":"public","_id":"26627","project":[{"_id":"53","name":"TRR 142"},{"name":"TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"_id":"52","name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"_id":"168","name":"TRR 142 - B07: TRR 142 - Subproject B07"}],"department":[{"_id":"296"},{"_id":"295"},{"_id":"230"},{"_id":"429"},{"_id":"15"},{"_id":"170"},{"_id":"35"}],"user_id":"16199","article_type":"original","isi":"1","article_number":"015002","file_date_updated":"2021-11-22T17:57:00Z","funded_apc":"1","quality_controlled":"1","issue":"1","year":"2022","publisher":"IOP Publishing","date_created":"2021-10-20T13:00:04Z","title":"Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4","publication":"Journal of Physics: Materials","abstract":[{"text":"Many-body perturbation theory based on density-functional theory calculations is used to determine the quasiparticle band structures and the dielectric functions of the isomorphic ferroelectrics rubidium titanyl phosphate (RbTiOPO4) and potassium titanyl arsenide (KTiOAsO4). Self-energy corrections of more than 2 eV are found to widen the transport band gaps of both materials considerably to 5.3 and 5.2 eV, respectively. At the same time, both materials are characterized by strong exciton binding energies of 1.4 and 1.5 eV, respectively. The solution of the Bethe-Salpeter equation based on the quasiparticle energies results in onsets of the optical absorption within the range of the measured data.","lang":"eng"}],"file":[{"content_type":"application/pdf","relation":"main_file","date_updated":"2021-11-22T17:57:00Z","date_created":"2021-11-22T17:57:00Z","creator":"schindlm","file_size":2687065,"description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4","file_id":"27705","file_name":"Neufeld_2022_J._Phys._Mater._5_015002.pdf","access_level":"open_access"}],"external_id":{"isi":["000721060500001"]},"ddc":["530"],"language":[{"iso":"eng"}]},{"_id":"29808","user_id":"16199","department":[{"_id":"296"},{"_id":"170"},{"_id":"15"},{"_id":"35"}],"language":[{"iso":"ger"}],"type":"book_chapter","publication":"Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre","editor":[{"last_name":"Gerick","full_name":"Gerick, Julia","first_name":"Julia"},{"last_name":"Sommer","full_name":"Sommer, Angela","first_name":"Angela"},{"full_name":"Zimmermann, Germo","last_name":"Zimmermann","first_name":"Germo"}],"abstract":[{"lang":"ger","text":"Dieses Format eignet sich, um zu prüfen, inwieweit Studierende Computersimulationen und eigene kleine Programme zur Lösung typischer Probleme ihres Fachs nutzen können. Wie bei Klausuren erfolgt die Bearbeitung in begrenzter Zeit und unter Aufsicht, wird aber am Computer durchgeführt und beinhaltet neben der Programmierung auch vor- und nachbereitende Aufgaben im Kontext der fachlichen Anwendung."}],"status":"public","date_updated":"2023-04-20T14:55:58Z","publisher":"Waxmann","author":[{"full_name":"Schindlmayr, Arno","id":"458","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","first_name":"Arno"}],"date_created":"2022-02-11T11:13:37Z","title":"Programmierung und Computersimulationen","doi":"10.36198/9783838558592","publication_status":"published","quality_controlled":"1","publication_identifier":{"isbn":["9783825258597"],"eisbn":["9783838558592"]},"edition":"2","year":"2022","place":"Münster","citation":{"ama":"Schindlmayr A. Programmierung und Computersimulationen. In: Gerick J, Sommer A, Zimmermann G, eds. <i>Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i>. 2nd ed. Waxmann; 2022:270-274. doi:<a href=\"https://doi.org/10.36198/9783838558592\">10.36198/9783838558592</a>","ieee":"A. Schindlmayr, “Programmierung und Computersimulationen,” in <i>Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i>, 2nd ed., J. Gerick, A. Sommer, and G. Zimmermann, Eds. Münster: Waxmann, 2022, pp. 270–274.","chicago":"Schindlmayr, Arno. “Programmierung und Computersimulationen.” In <i>Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i>, edited by Julia Gerick, Angela Sommer, and Germo Zimmermann, 2nd ed., 270–74. Münster: Waxmann, 2022. <a href=\"https://doi.org/10.36198/9783838558592\">https://doi.org/10.36198/9783838558592</a>.","mla":"Schindlmayr, Arno. “Programmierung und Computersimulationen.” <i>Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i>, edited by Julia Gerick et al., 2nd ed., Waxmann, 2022, pp. 270–74, doi:<a href=\"https://doi.org/10.36198/9783838558592\">10.36198/9783838558592</a>.","bibtex":"@inbook{Schindlmayr_2022, place={Münster}, edition={2}, title={Programmierung und Computersimulationen}, DOI={<a href=\"https://doi.org/10.36198/9783838558592\">10.36198/9783838558592</a>}, booktitle={Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre}, publisher={Waxmann}, author={Schindlmayr, Arno}, editor={Gerick, Julia and Sommer, Angela and Zimmermann, Germo}, year={2022}, pages={270–274} }","short":"A. Schindlmayr, in: J. Gerick, A. Sommer, G. Zimmermann (Eds.), Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre, 2nd ed., Waxmann, Münster, 2022, pp. 270–274.","apa":"Schindlmayr, A. (2022). Programmierung und Computersimulationen. In J. Gerick, A. Sommer, &#38; G. Zimmermann (Eds.), <i>Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i> (2nd ed., pp. 270–274). Waxmann. <a href=\"https://doi.org/10.36198/9783838558592\">https://doi.org/10.36198/9783838558592</a>"},"page":"270-274"},{"publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["2073-4352"]},"citation":{"apa":"Schmidt, F., Kozub, A. L., Gerstmann, U., Schmidt, W. G., &#38; Schindlmayr, A. (2022). A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate. <i>Crystals</i>, <i>12</i>(11), Article 1586. <a href=\"https://doi.org/10.3390/cryst12111586\">https://doi.org/10.3390/cryst12111586</a>","mla":"Schmidt, Falko, et al. “A Density-Functional Theory Study of Hole and Defect-Bound Exciton Polarons in Lithium Niobate.” <i>Crystals</i>, vol. 12, no. 11, 1586, MDPI AG, 2022, doi:<a href=\"https://doi.org/10.3390/cryst12111586\">10.3390/cryst12111586</a>.","short":"F. Schmidt, A.L. Kozub, U. Gerstmann, W.G. Schmidt, A. Schindlmayr, Crystals 12 (2022).","bibtex":"@article{Schmidt_Kozub_Gerstmann_Schmidt_Schindlmayr_2022, title={A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate}, volume={12}, DOI={<a href=\"https://doi.org/10.3390/cryst12111586\">10.3390/cryst12111586</a>}, number={111586}, journal={Crystals}, publisher={MDPI AG}, author={Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}, year={2022} }","chicago":"Schmidt, Falko, Agnieszka L. Kozub, Uwe Gerstmann, Wolf Gero Schmidt, and Arno Schindlmayr. “A Density-Functional Theory Study of Hole and Defect-Bound Exciton Polarons in Lithium Niobate.” <i>Crystals</i> 12, no. 11 (2022). <a href=\"https://doi.org/10.3390/cryst12111586\">https://doi.org/10.3390/cryst12111586</a>.","ieee":"F. Schmidt, A. L. Kozub, U. Gerstmann, W. G. Schmidt, and A. Schindlmayr, “A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate,” <i>Crystals</i>, vol. 12, no. 11, Art. no. 1586, 2022, doi: <a href=\"https://doi.org/10.3390/cryst12111586\">10.3390/cryst12111586</a>.","ama":"Schmidt F, Kozub AL, Gerstmann U, Schmidt WG, Schindlmayr A. A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate. <i>Crystals</i>. 2022;12(11). doi:<a href=\"https://doi.org/10.3390/cryst12111586\">10.3390/cryst12111586</a>"},"intvolume":"        12","author":[{"orcid":"0000-0002-5071-5528","last_name":"Schmidt","full_name":"Schmidt, Falko","id":"35251","first_name":"Falko"},{"first_name":"Agnieszka L.","last_name":"Kozub","orcid":"0000-0001-6584-0201","full_name":"Kozub, Agnieszka L.","id":"77566"},{"first_name":"Uwe","id":"171","full_name":"Gerstmann, Uwe","orcid":"0000-0002-4476-223X","last_name":"Gerstmann"},{"first_name":"Wolf Gero","full_name":"Schmidt, Wolf Gero","id":"468","last_name":"Schmidt","orcid":"0000-0002-2717-5076"},{"full_name":"Schindlmayr, Arno","id":"458","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","first_name":"Arno"}],"volume":12,"oa":"1","date_updated":"2025-09-18T13:28:05Z","doi":"10.3390/cryst12111586","type":"journal_article","status":"public","user_id":"16199","department":[{"_id":"15"},{"_id":"296"},{"_id":"170"},{"_id":"295"},{"_id":"35"},{"_id":"230"},{"_id":"429"},{"_id":"27"}],"project":[{"name":"TRR 142: TRR 142","_id":"53"},{"_id":"54","name":"TRR 142 - A: TRR 142 - Project Area A"},{"name":"TRR 142 - B: TRR 142 - Project Area B","_id":"55"},{"_id":"69","name":"TRR 142 - B04: TRR 142 - Subproject B04"},{"name":"TRR 142 - B07: TRR 142 - Subproject B07","_id":"168"},{"name":"TRR 142 - A11: TRR 142 - Subproject A11","_id":"166"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"_id":"44088","file_date_updated":"2023-06-12T00:22:51Z","article_number":"1586","article_type":"original","isi":"1","issue":"11","quality_controlled":"1","year":"2022","date_created":"2023-04-20T13:52:44Z","publisher":"MDPI AG","title":"A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate","publication":"Crystals","file":[{"relation":"main_file","content_type":"application/pdf","file_size":1762554,"description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate","file_id":"45570","file_name":"crystals-12-01586-v2.pdf","access_level":"open_access","date_updated":"2023-06-12T00:22:51Z","date_created":"2023-06-11T23:59:27Z","creator":"schindlm"}],"abstract":[{"lang":"eng","text":"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."}],"external_id":{"isi":["000895837200001"]},"language":[{"iso":"eng"}],"ddc":["530"]},{"type":"book_chapter","status":"public","editor":[{"last_name":"Corradi","full_name":"Corradi, Gábor","first_name":"Gábor"},{"first_name":"László","last_name":"Kovács","full_name":"Kovács, László"}],"user_id":"16199","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"15"},{"_id":"170"},{"_id":"35"},{"_id":"790"}],"project":[{"_id":"53","name":"TRR 142: TRR 142"},{"_id":"55","name":"TRR 142 - B: TRR 142 - Project Area B"},{"_id":"69","name":"TRR 142 - B4: TRR 142 - Subproject B4"},{"_id":"54","name":"TRR 142 - A: TRR 142 - Project Area A"},{"name":"TRR 142 - A11: TRR 142 - Subproject A11","_id":"166"},{"_id":"168","name":"TRR 142 - B07: TRR 142 - Subproject B07"},{"_id":"52","name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"_id":"53","name":"TRR 142: Maßgeschneiderte nichtlineare Photonik: Von grundlegenden Konzepten zu funktionellen Strukturen"}],"_id":"30288","publication_status":"published","publication_identifier":{"eisbn":["978-3-0365-3339-1"],"isbn":["978-3-0365-3340-7"]},"citation":{"apa":"Schmidt, F., Kozub, A. L., Gerstmann, U., Schmidt, W. G., &#38; Schindlmayr, A. (2022). Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response. In G. Corradi &#38; L. Kovács (Eds.), <i>New Trends in Lithium Niobate: From Bulk to Nanocrystals</i> (pp. 231–248). MDPI. <a href=\"https://doi.org/10.3390/books978-3-0365-3339-1\">https://doi.org/10.3390/books978-3-0365-3339-1</a>","bibtex":"@inbook{Schmidt_Kozub_Gerstmann_Schmidt_Schindlmayr_2022, place={Basel}, title={Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response}, DOI={<a href=\"https://doi.org/10.3390/books978-3-0365-3339-1\">10.3390/books978-3-0365-3339-1</a>}, booktitle={New Trends in Lithium Niobate: From Bulk to Nanocrystals}, publisher={MDPI}, author={Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}, editor={Corradi, Gábor and Kovács, László}, year={2022}, pages={231–248} }","mla":"Schmidt, Falko, et al. “Electron Polarons in Lithium Niobate: Charge Localization, Lattice Deformation, and Optical Response.” <i>New Trends in Lithium Niobate: From Bulk to Nanocrystals</i>, edited by Gábor Corradi and László Kovács, MDPI, 2022, pp. 231–48, doi:<a href=\"https://doi.org/10.3390/books978-3-0365-3339-1\">10.3390/books978-3-0365-3339-1</a>.","short":"F. Schmidt, A.L. Kozub, U. Gerstmann, W.G. Schmidt, A. Schindlmayr, in: G. Corradi, L. Kovács (Eds.), New Trends in Lithium Niobate: From Bulk to Nanocrystals, MDPI, Basel, 2022, pp. 231–248.","ama":"Schmidt F, Kozub AL, Gerstmann U, Schmidt WG, Schindlmayr A. Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response. In: Corradi G, Kovács L, eds. <i>New Trends in Lithium Niobate: From Bulk to Nanocrystals</i>. MDPI; 2022:231-248. doi:<a href=\"https://doi.org/10.3390/books978-3-0365-3339-1\">10.3390/books978-3-0365-3339-1</a>","ieee":"F. Schmidt, A. L. Kozub, U. Gerstmann, W. G. Schmidt, and A. Schindlmayr, “Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response,” in <i>New Trends in Lithium Niobate: From Bulk to Nanocrystals</i>, G. Corradi and L. Kovács, Eds. Basel: MDPI, 2022, pp. 231–248.","chicago":"Schmidt, Falko, Agnieszka L. Kozub, Uwe Gerstmann, Wolf Gero Schmidt, and Arno Schindlmayr. “Electron Polarons in Lithium Niobate: Charge Localization, Lattice Deformation, and Optical Response.” In <i>New Trends in Lithium Niobate: From Bulk to Nanocrystals</i>, edited by Gábor Corradi and László Kovács, 231–48. Basel: MDPI, 2022. <a href=\"https://doi.org/10.3390/books978-3-0365-3339-1\">https://doi.org/10.3390/books978-3-0365-3339-1</a>."},"page":"231-248","place":"Basel","author":[{"full_name":"Schmidt, Falko","id":"35251","orcid":"0000-0002-5071-5528","last_name":"Schmidt","first_name":"Falko"},{"full_name":"Kozub, Agnieszka L.","id":"77566","last_name":"Kozub","orcid":"https://orcid.org/0000-0001-6584-0201","first_name":"Agnieszka L."},{"full_name":"Gerstmann, Uwe","id":"171","last_name":"Gerstmann","orcid":"0000-0002-4476-223X","first_name":"Uwe"},{"last_name":"Schmidt","orcid":"0000-0002-2717-5076","full_name":"Schmidt, Wolf Gero","id":"468","first_name":"Wolf Gero"},{"first_name":"Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","full_name":"Schindlmayr, Arno","id":"458"}],"date_updated":"2025-12-05T14:00:04Z","doi":"10.3390/books978-3-0365-3339-1","publication":"New Trends in Lithium Niobate: From Bulk to Nanocrystals","abstract":[{"text":"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.","lang":"eng"}],"language":[{"iso":"eng"}],"ddc":["530"],"quality_controlled":"1","year":"2022","date_created":"2022-03-13T15:28:47Z","publisher":"MDPI","title":"Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response"},{"file":[{"relation":"main_file","content_type":"application/pdf","file_size":3042827,"description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response","access_level":"open_access","file_id":"22163","file_name":"crystals-11-00542.pdf","date_updated":"2021-05-13T16:51:41Z","date_created":"2021-05-13T16:47:11Z","creator":"schindlm"}],"abstract":[{"lang":"eng","text":"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."}],"publication":"Crystals","language":[{"iso":"eng"}],"ddc":["530"],"external_id":{"isi":["000653822700001"]},"year":"2021","quality_controlled":"1","title":"Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response","date_created":"2021-05-03T09:36:13Z","publisher":"MDPI","status":"public","type":"journal_article","file_date_updated":"2021-05-13T16:51:41Z","funded_apc":"1","article_type":"original","isi":"1","user_id":"171","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"15"},{"_id":"170"},{"_id":"35"},{"_id":"790"}],"project":[{"name":"TRR 142","_id":"53"},{"_id":"55","name":"TRR 142 - Project Area B"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"_id":"21946","citation":{"apa":"Schmidt, F., Kozub, A. L., Gerstmann, U., Schmidt, W. G., &#38; Schindlmayr, A. (2021). Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response. <i>Crystals</i>, <i>11</i>, 542. <a href=\"https://doi.org/10.3390/cryst11050542\">https://doi.org/10.3390/cryst11050542</a>","bibtex":"@article{Schmidt_Kozub_Gerstmann_Schmidt_Schindlmayr_2021, title={Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response}, volume={11}, DOI={<a href=\"https://doi.org/10.3390/cryst11050542\">10.3390/cryst11050542</a>}, journal={Crystals}, publisher={MDPI}, author={Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr, Arno}, year={2021}, pages={542} }","short":"F. Schmidt, A.L. Kozub, U. Gerstmann, W.G. Schmidt, A. Schindlmayr, Crystals 11 (2021) 542.","mla":"Schmidt, Falko, et al. “Electron Polarons in Lithium Niobate: Charge Localization, Lattice Deformation, and Optical Response.” <i>Crystals</i>, vol. 11, MDPI, 2021, p. 542, doi:<a href=\"https://doi.org/10.3390/cryst11050542\">10.3390/cryst11050542</a>.","ama":"Schmidt F, Kozub AL, Gerstmann U, Schmidt WG, Schindlmayr A. Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response. <i>Crystals</i>. 2021;11:542. doi:<a href=\"https://doi.org/10.3390/cryst11050542\">10.3390/cryst11050542</a>","chicago":"Schmidt, Falko, Agnieszka L. Kozub, Uwe Gerstmann, Wolf Gero Schmidt, and Arno Schindlmayr. “Electron Polarons in Lithium Niobate: Charge Localization, Lattice Deformation, and Optical Response.” <i>Crystals</i> 11 (2021): 542. <a href=\"https://doi.org/10.3390/cryst11050542\">https://doi.org/10.3390/cryst11050542</a>.","ieee":"F. Schmidt, A. L. Kozub, U. Gerstmann, W. G. Schmidt, and A. Schindlmayr, “Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response,” <i>Crystals</i>, vol. 11, p. 542, 2021, doi: <a href=\"https://doi.org/10.3390/cryst11050542\">10.3390/cryst11050542</a>."},"page":"542","intvolume":"        11","publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["2073-4352"]},"doi":"10.3390/cryst11050542","author":[{"id":"35251","full_name":"Schmidt, Falko","orcid":"0000-0002-5071-5528","last_name":"Schmidt","first_name":"Falko"},{"first_name":"Agnieszka L.","last_name":"Kozub","orcid":"https://orcid.org/0000-0001-6584-0201","full_name":"Kozub, Agnieszka L.","id":"77566"},{"first_name":"Uwe","orcid":"0000-0002-4476-223X","last_name":"Gerstmann","full_name":"Gerstmann, Uwe","id":"171"},{"first_name":"Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt","full_name":"Schmidt, Wolf Gero","id":"468"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","id":"458","full_name":"Schindlmayr, Arno"}],"volume":11,"date_updated":"2023-04-21T11:20:15Z","oa":"1"},{"year":"2021","quality_controlled":"1","issue":"8","title":"Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory","publisher":"EDP Sciences, Società Italiana di Fisica and Springer","date_created":"2021-08-08T21:21:42Z","abstract":[{"text":"We perform a theoretical analysis of the structural and electronic properties of sodium potassium niobate K1-xNaxNbO3 in the orthorhombic room-temperature phase, based on density-functional theory in combination with the supercell approach. Our results for x=0 and x=0.5 are in very good agreement with experimental measurements and establish that the lattice parameters decrease linearly with increasing Na contents, disproving earlier theoretical studies based on the virtual-crystal approximation that claimed a highly nonlinear behavior with a significant structural distortion and volume reduction in K0.5Na0.5NbO3 compared to both end members of the solid solution. Furthermore, we find that the electronic band gap varies very little between x=0 and x=0.5, reflecting the small changes in the lattice parameters.","lang":"eng"}],"file":[{"content_type":"application/pdf","creator":"schindlm","file_name":"BidaraguppeRamesh2021_Article_LatticeParametersAndElectronic.pdf","file_size":850389,"relation":"main_file","date_created":"2021-09-02T08:05:06Z","date_updated":"2021-09-02T08:05:06Z","file_id":"23679","access_level":"open_access","title":"Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory","description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)"}],"publication":"The European Physical Journal B","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000687163200002"]},"citation":{"chicago":"Bidaraguppe Ramesh, Nithin, Falko Schmidt, and Arno Schindlmayr. “Lattice Parameters and Electronic Band Gap of Orthorhombic Potassium Sodium Niobate K0.5Na0.5NbO3 from Density-Functional Theory.” <i>The European Physical Journal B</i> 94, no. 8 (2021). <a href=\"https://doi.org/10.1140/epjb/s10051-021-00179-8\">https://doi.org/10.1140/epjb/s10051-021-00179-8</a>.","ieee":"N. Bidaraguppe Ramesh, F. Schmidt, and A. Schindlmayr, “Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory,” <i>The European Physical Journal B</i>, vol. 94, no. 8, Art. no. 169, 2021, doi: <a href=\"https://doi.org/10.1140/epjb/s10051-021-00179-8\">10.1140/epjb/s10051-021-00179-8</a>.","ama":"Bidaraguppe Ramesh N, Schmidt F, Schindlmayr A. Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory. <i>The European Physical Journal B</i>. 2021;94(8). doi:<a href=\"https://doi.org/10.1140/epjb/s10051-021-00179-8\">10.1140/epjb/s10051-021-00179-8</a>","mla":"Bidaraguppe Ramesh, Nithin, et al. “Lattice Parameters and Electronic Band Gap of Orthorhombic Potassium Sodium Niobate K0.5Na0.5NbO3 from Density-Functional Theory.” <i>The European Physical Journal B</i>, vol. 94, no. 8, 169, EDP Sciences, Società Italiana di Fisica and Springer, 2021, doi:<a href=\"https://doi.org/10.1140/epjb/s10051-021-00179-8\">10.1140/epjb/s10051-021-00179-8</a>.","bibtex":"@article{Bidaraguppe Ramesh_Schmidt_Schindlmayr_2021, title={Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory}, volume={94}, DOI={<a href=\"https://doi.org/10.1140/epjb/s10051-021-00179-8\">10.1140/epjb/s10051-021-00179-8</a>}, number={8169}, journal={The European Physical Journal B}, publisher={EDP Sciences, Società Italiana di Fisica and Springer}, author={Bidaraguppe Ramesh, Nithin and Schmidt, Falko and Schindlmayr, Arno}, year={2021} }","short":"N. Bidaraguppe Ramesh, F. Schmidt, A. Schindlmayr, The European Physical Journal B 94 (2021).","apa":"Bidaraguppe Ramesh, N., Schmidt, F., &#38; Schindlmayr, A. (2021). Lattice parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory. <i>The European Physical Journal B</i>, <i>94</i>(8), Article 169. <a href=\"https://doi.org/10.1140/epjb/s10051-021-00179-8\">https://doi.org/10.1140/epjb/s10051-021-00179-8</a>"},"intvolume":"        94","publication_status":"published","publication_identifier":{"issn":["1434-6028"],"eissn":["1434-6036"]},"has_accepted_license":"1","doi":"10.1140/epjb/s10051-021-00179-8","date_updated":"2023-04-20T14:56:25Z","oa":"1","author":[{"first_name":"Nithin","id":"70064","full_name":"Bidaraguppe Ramesh, Nithin","last_name":"Bidaraguppe Ramesh"},{"first_name":"Falko","full_name":"Schmidt, Falko","id":"35251","last_name":"Schmidt","orcid":"0000-0002-5071-5528"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458"}],"volume":94,"status":"public","type":"journal_article","article_number":"169","isi":"1","article_type":"original","file_date_updated":"2021-09-02T08:05:06Z","project":[{"name":"TRR 142","_id":"53"},{"name":"TRR 142 - Project Area B","_id":"55"},{"_id":"69","name":"TRR 142 - Subproject B4"}],"_id":"22960","user_id":"16199","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"15"},{"_id":"170"},{"_id":"35"}]},{"doi":"10.1103/PhysRevB.104.039901","date_updated":"2023-04-20T14:57:09Z","oa":"1","author":[{"first_name":"Christoph","last_name":"Friedrich","full_name":"Friedrich, Christoph"},{"first_name":"Stefan","last_name":"Blügel","full_name":"Blügel, Stefan"},{"last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","full_name":"Schindlmayr, Arno","id":"458","first_name":"Arno"}],"volume":104,"citation":{"chicago":"Friedrich, Christoph, Stefan Blügel, and Arno Schindlmayr. “Erratum: Efficient Implementation of the GW Approximation within the All-Electron FLAPW Method [Phys. Rev. B 81, 125102 (2010)].” <i>Physical Review B</i> 104, no. 3 (2021). <a href=\"https://doi.org/10.1103/PhysRevB.104.039901\">https://doi.org/10.1103/PhysRevB.104.039901</a>.","ieee":"C. Friedrich, S. Blügel, and A. Schindlmayr, “Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)],” <i>Physical Review B</i>, vol. 104, no. 3, Art. no. 039901, 2021, doi: <a href=\"https://doi.org/10.1103/PhysRevB.104.039901\">10.1103/PhysRevB.104.039901</a>.","ama":"Friedrich C, Blügel S, Schindlmayr A. Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]. <i>Physical Review B</i>. 2021;104(3). doi:<a href=\"https://doi.org/10.1103/PhysRevB.104.039901\">10.1103/PhysRevB.104.039901</a>","apa":"Friedrich, C., Blügel, S., &#38; Schindlmayr, A. (2021). Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]. <i>Physical Review B</i>, <i>104</i>(3), Article 039901. <a href=\"https://doi.org/10.1103/PhysRevB.104.039901\">https://doi.org/10.1103/PhysRevB.104.039901</a>","bibtex":"@article{Friedrich_Blügel_Schindlmayr_2021, title={Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]}, volume={104}, DOI={<a href=\"https://doi.org/10.1103/PhysRevB.104.039901\">10.1103/PhysRevB.104.039901</a>}, number={3039901}, journal={Physical Review B}, publisher={American Physical Society}, author={Friedrich, Christoph and Blügel, Stefan and Schindlmayr, Arno}, year={2021} }","short":"C. Friedrich, S. Blügel, A. Schindlmayr, Physical Review B 104 (2021).","mla":"Friedrich, Christoph, et al. “Erratum: Efficient Implementation of the GW Approximation within the All-Electron FLAPW Method [Phys. Rev. B 81, 125102 (2010)].” <i>Physical Review B</i>, vol. 104, no. 3, 039901, American Physical Society, 2021, doi:<a href=\"https://doi.org/10.1103/PhysRevB.104.039901\">10.1103/PhysRevB.104.039901</a>."},"intvolume":"       104","publication_status":"published","has_accepted_license":"1","publication_identifier":{"issn":["2469-9950"],"eissn":["2469-9969"]},"related_material":{"record":[{"status":"public","id":"18558","relation":"other"}]},"article_number":"039901","isi":"1","file_date_updated":"2021-07-15T20:16:55Z","_id":"22761","user_id":"16199","department":[{"_id":"296"},{"_id":"15"},{"_id":"170"}],"status":"public","type":"journal_article","title":"Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]","publisher":"American Physical Society","date_created":"2021-07-15T19:59:00Z","year":"2021","quality_controlled":"1","issue":"3","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000671587300006"]},"file":[{"content_type":"application/pdf","file_size":180926,"file_name":"PhysRevB.104.039901.pdf","creator":"schindlm","relation":"main_file","title":"Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]","description":"© 2021 American Physical Society","access_level":"open_access","file_id":"22763","date_updated":"2021-07-15T20:16:55Z","date_created":"2021-07-15T20:16:55Z"}],"publication":"Physical Review B"},{"status":"public","type":"journal_article","isi":"1","article_type":"original","file_date_updated":"2021-11-18T20:49:19Z","project":[{"_id":"53","name":"TRR 142"},{"_id":"55","name":"TRR 142 - Project Area B"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"_id":"52","name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"_id":"23418","user_id":"171","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"15"},{"_id":"170"},{"_id":"790"}],"citation":{"apa":"Kozub, A. L., Schindlmayr, A., Gerstmann, U., &#38; Schmidt, W. G. (2021). Polaronic enhancement of second-harmonic generation in lithium niobate. <i>Physical Review B</i>, <i>104</i>, 174110. <a href=\"https://doi.org/10.1103/PhysRevB.104.174110\">https://doi.org/10.1103/PhysRevB.104.174110</a>","short":"A.L. Kozub, A. Schindlmayr, U. Gerstmann, W.G. Schmidt, Physical Review B 104 (2021) 174110.","bibtex":"@article{Kozub_Schindlmayr_Gerstmann_Schmidt_2021, title={Polaronic enhancement of second-harmonic generation in lithium niobate}, volume={104}, DOI={<a href=\"https://doi.org/10.1103/PhysRevB.104.174110\">10.1103/PhysRevB.104.174110</a>}, journal={Physical Review B}, publisher={American Physical Society}, author={Kozub, Agnieszka L. and Schindlmayr, Arno and Gerstmann, Uwe and Schmidt, Wolf Gero}, year={2021}, pages={174110} }","mla":"Kozub, Agnieszka L., et al. “Polaronic Enhancement of Second-Harmonic Generation in Lithium Niobate.” <i>Physical Review B</i>, vol. 104, American Physical Society, 2021, p. 174110, doi:<a href=\"https://doi.org/10.1103/PhysRevB.104.174110\">10.1103/PhysRevB.104.174110</a>.","ama":"Kozub AL, Schindlmayr A, Gerstmann U, Schmidt WG. Polaronic enhancement of second-harmonic generation in lithium niobate. <i>Physical Review B</i>. 2021;104:174110. doi:<a href=\"https://doi.org/10.1103/PhysRevB.104.174110\">10.1103/PhysRevB.104.174110</a>","ieee":"A. L. Kozub, A. Schindlmayr, U. Gerstmann, and W. G. Schmidt, “Polaronic enhancement of second-harmonic generation in lithium niobate,” <i>Physical Review B</i>, vol. 104, p. 174110, 2021, doi: <a href=\"https://doi.org/10.1103/PhysRevB.104.174110\">10.1103/PhysRevB.104.174110</a>.","chicago":"Kozub, Agnieszka L., Arno Schindlmayr, Uwe Gerstmann, and Wolf Gero Schmidt. “Polaronic Enhancement of Second-Harmonic Generation in Lithium Niobate.” <i>Physical Review B</i> 104 (2021): 174110. <a href=\"https://doi.org/10.1103/PhysRevB.104.174110\">https://doi.org/10.1103/PhysRevB.104.174110</a>."},"page":"174110","intvolume":"       104","publication_status":"published","publication_identifier":{"issn":["2469-9950"],"eissn":["2469-9969"]},"has_accepted_license":"1","doi":"10.1103/PhysRevB.104.174110","oa":"1","date_updated":"2023-04-21T11:15:30Z","author":[{"full_name":"Kozub, Agnieszka L.","id":"77566","last_name":"Kozub","orcid":"https://orcid.org/0000-0001-6584-0201","first_name":"Agnieszka L."},{"first_name":"Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","id":"458","full_name":"Schindlmayr, Arno"},{"first_name":"Uwe","full_name":"Gerstmann, Uwe","id":"171","last_name":"Gerstmann","orcid":"0000-0002-4476-223X"},{"first_name":"Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt","full_name":"Schmidt, Wolf Gero","id":"468"}],"volume":104,"abstract":[{"lang":"eng","text":"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."}],"file":[{"relation":"main_file","date_created":"2021-11-18T20:49:19Z","date_updated":"2021-11-18T20:49:19Z","file_id":"27577","access_level":"open_access","description":"© 2021 American Physical Society","title":"Polaronic enhancement of second-harmonic generation in lithium niobate","content_type":"application/pdf","creator":"schindlm","file_name":"PhysRevB.104.174110.pdf","file_size":804012}],"publication":"Physical Review B","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000720931400007"],"arxiv":["2106.01145"]},"year":"2021","quality_controlled":"1","title":"Polaronic enhancement of second-harmonic generation in lithium niobate","publisher":"American Physical Society","date_created":"2021-08-16T19:09:46Z"},{"citation":{"ieee":"F. Schmidt <i>et al.</i>, “Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations,” <i>Physical Review Research</i>, vol. 2, no. 4, Art. no. 043002, 2020, doi: <a href=\"https://doi.org/10.1103/PhysRevResearch.2.043002\">10.1103/PhysRevResearch.2.043002</a>.","chicago":"Schmidt, Falko, Agnieszka L. Kozub, Timur Biktagirov, Christof Eigner, Christine Silberhorn, Arno Schindlmayr, Wolf Gero Schmidt, and Uwe Gerstmann. “Free and Defect-Bound (Bi)Polarons in LiNbO3: Atomic Structure and Spectroscopic Signatures from Ab Initio Calculations.” <i>Physical Review Research</i> 2, no. 4 (2020). <a href=\"https://doi.org/10.1103/PhysRevResearch.2.043002\">https://doi.org/10.1103/PhysRevResearch.2.043002</a>.","ama":"Schmidt F, Kozub AL, Biktagirov T, et al. Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations. <i>Physical Review Research</i>. 2020;2(4). doi:<a href=\"https://doi.org/10.1103/PhysRevResearch.2.043002\">10.1103/PhysRevResearch.2.043002</a>","mla":"Schmidt, Falko, et al. “Free and Defect-Bound (Bi)Polarons in LiNbO3: Atomic Structure and Spectroscopic Signatures from Ab Initio Calculations.” <i>Physical Review Research</i>, vol. 2, no. 4, 043002, American Physical Society, 2020, doi:<a href=\"https://doi.org/10.1103/PhysRevResearch.2.043002\">10.1103/PhysRevResearch.2.043002</a>.","short":"F. Schmidt, A.L. Kozub, T. Biktagirov, C. Eigner, C. Silberhorn, A. Schindlmayr, W.G. Schmidt, U. Gerstmann, Physical Review Research 2 (2020).","bibtex":"@article{Schmidt_Kozub_Biktagirov_Eigner_Silberhorn_Schindlmayr_Schmidt_Gerstmann_2020, title={Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations}, volume={2}, DOI={<a href=\"https://doi.org/10.1103/PhysRevResearch.2.043002\">10.1103/PhysRevResearch.2.043002</a>}, number={4043002}, journal={Physical Review Research}, publisher={American Physical Society}, 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}, year={2020} }","apa":"Schmidt, F., Kozub, A. L., Biktagirov, T., Eigner, C., Silberhorn, C., Schindlmayr, A., Schmidt, W. G., &#38; Gerstmann, U. (2020). Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations. <i>Physical Review Research</i>, <i>2</i>(4), Article 043002. <a href=\"https://doi.org/10.1103/PhysRevResearch.2.043002\">https://doi.org/10.1103/PhysRevResearch.2.043002</a>"},"intvolume":"         2","publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["2643-1564"]},"doi":"10.1103/PhysRevResearch.2.043002","oa":"1","date_updated":"2023-04-20T16:06:21Z","author":[{"first_name":"Falko","id":"35251","full_name":"Schmidt, Falko","orcid":"0000-0002-5071-5528","last_name":"Schmidt"},{"last_name":"Kozub","orcid":"https://orcid.org/0000-0001-6584-0201","full_name":"Kozub, Agnieszka L.","id":"77566","first_name":"Agnieszka L."},{"last_name":"Biktagirov","full_name":"Biktagirov, Timur","id":"65612","first_name":"Timur"},{"first_name":"Christof","full_name":"Eigner, Christof","id":"13244","orcid":"https://orcid.org/0000-0002-5693-3083","last_name":"Eigner"},{"first_name":"Christine","last_name":"Silberhorn","full_name":"Silberhorn, Christine","id":"26263"},{"first_name":"Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","full_name":"Schindlmayr, Arno","id":"458"},{"id":"468","full_name":"Schmidt, Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt","first_name":"Wolf Gero"},{"first_name":"Uwe","last_name":"Gerstmann","orcid":"0000-0002-4476-223X","id":"171","full_name":"Gerstmann, Uwe"}],"volume":2,"status":"public","type":"journal_article","isi":"1","article_type":"original","article_number":"043002","file_date_updated":"2020-10-02T07:37:24Z","project":[{"_id":"53","name":"TRR 142"},{"_id":"55","name":"TRR 142 - Project Area B"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"_id":"52","name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"_id":"19190","user_id":"16199","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"288"},{"_id":"15"},{"_id":"170"},{"_id":"35"},{"_id":"790"}],"year":"2020","quality_controlled":"1","issue":"4","title":"Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations","publisher":"American Physical Society","date_created":"2020-09-09T09:35:21Z","abstract":[{"lang":"eng","text":"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 \r\npolarons 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 \r\nNb_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."}],"file":[{"relation":"main_file","access_level":"open_access","file_id":"19843","description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations","date_created":"2020-10-02T07:27:38Z","date_updated":"2020-10-02T07:37:24Z","content_type":"application/pdf","file_name":"PhysRevResearch.2.043002.pdf","file_size":1955183,"creator":"schindlm"}],"publication":"Physical Review Research","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000604206300002"]}},{"doi":"10.1103/PhysRevMaterials.3.054401","volume":3,"author":[{"full_name":"Schmidt, Falko","id":"35251","orcid":"0000-0002-5071-5528","last_name":"Schmidt","first_name":"Falko"},{"first_name":"Arthur","last_name":"Riefer","full_name":"Riefer, Arthur"},{"first_name":"Wolf Gero","last_name":"Schmidt","orcid":"0000-0002-2717-5076","id":"468","full_name":"Schmidt, Wolf Gero"},{"id":"458","full_name":"Schindlmayr, Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","first_name":"Arno"},{"first_name":"Mirco","last_name":"Imlau","full_name":"Imlau, Mirco"},{"first_name":"Florian","last_name":"Dobener","full_name":"Dobener, Florian"},{"last_name":"Mengel","full_name":"Mengel, Nils","first_name":"Nils"},{"first_name":"Sangam","last_name":"Chatterjee","full_name":"Chatterjee, Sangam"},{"full_name":"Sanna, Simone","last_name":"Sanna","first_name":"Simone"}],"date_updated":"2023-04-20T14:20:33Z","oa":"1","intvolume":"         3","citation":{"ama":"Schmidt F, Riefer A, Schmidt WG, et al. Quasiparticle and excitonic effects in the optical response of KNbO3. <i>Physical Review Materials</i>. 2019;3(5). doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.3.054401\">10.1103/PhysRevMaterials.3.054401</a>","ieee":"F. Schmidt <i>et al.</i>, “Quasiparticle and excitonic effects in the optical response of KNbO3,” <i>Physical Review Materials</i>, vol. 3, no. 5, Art. no. 054401, 2019, doi: <a href=\"https://doi.org/10.1103/PhysRevMaterials.3.054401\">10.1103/PhysRevMaterials.3.054401</a>.","chicago":"Schmidt, Falko, Arthur Riefer, Wolf Gero Schmidt, Arno Schindlmayr, Mirco Imlau, Florian Dobener, Nils Mengel, Sangam Chatterjee, and Simone Sanna. “Quasiparticle and Excitonic Effects in the Optical Response of KNbO3.” <i>Physical Review Materials</i> 3, no. 5 (2019). <a href=\"https://doi.org/10.1103/PhysRevMaterials.3.054401\">https://doi.org/10.1103/PhysRevMaterials.3.054401</a>.","apa":"Schmidt, F., Riefer, A., Schmidt, W. G., Schindlmayr, A., Imlau, M., Dobener, F., Mengel, N., Chatterjee, S., &#38; Sanna, S. (2019). Quasiparticle and excitonic effects in the optical response of KNbO3. <i>Physical Review Materials</i>, <i>3</i>(5), Article 054401. <a href=\"https://doi.org/10.1103/PhysRevMaterials.3.054401\">https://doi.org/10.1103/PhysRevMaterials.3.054401</a>","mla":"Schmidt, Falko, et al. “Quasiparticle and Excitonic Effects in the Optical Response of KNbO3.” <i>Physical Review Materials</i>, vol. 3, no. 5, 054401, American Physical Society, 2019, doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.3.054401\">10.1103/PhysRevMaterials.3.054401</a>.","bibtex":"@article{Schmidt_Riefer_Schmidt_Schindlmayr_Imlau_Dobener_Mengel_Chatterjee_Sanna_2019, title={Quasiparticle and excitonic effects in the optical response of KNbO3}, volume={3}, DOI={<a href=\"https://doi.org/10.1103/PhysRevMaterials.3.054401\">10.1103/PhysRevMaterials.3.054401</a>}, number={5054401}, journal={Physical Review Materials}, publisher={American Physical Society}, author={Schmidt, Falko and Riefer, Arthur and Schmidt, Wolf Gero and Schindlmayr, Arno and Imlau, Mirco and Dobener, Florian and Mengel, Nils and Chatterjee, Sangam and Sanna, Simone}, year={2019} }","short":"F. Schmidt, A. Riefer, W.G. Schmidt, A. Schindlmayr, M. Imlau, F. Dobener, N. Mengel, S. Chatterjee, S. Sanna, Physical Review Materials 3 (2019)."},"publication_identifier":{"eissn":["2475-9953"]},"has_accepted_license":"1","publication_status":"published","file_date_updated":"2020-08-30T14:34:33Z","article_type":"original","article_number":"054401","isi":"1","department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"170"},{"_id":"35"}],"user_id":"16199","_id":"10014","project":[{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"_id":"53","name":"TRR 142"},{"_id":"55","name":"TRR 142 - Project Area B"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"status":"public","type":"journal_article","title":"Quasiparticle and excitonic effects in the optical response of KNbO3","date_created":"2019-05-29T06:55:29Z","publisher":"American Physical Society","year":"2019","issue":"5","quality_controlled":"1","language":[{"iso":"eng"}],"ddc":["530"],"external_id":{"isi":["000467044000003"]},"file":[{"relation":"main_file","content_type":"application/pdf","file_name":"PhysRevMaterials.3.054401.pdf","access_level":"open_access","file_id":"18465","title":"Quasiparticle and excitonic effects in the optical response of KNbO3","description":"© 2019 American Physical Society","file_size":1949504,"creator":"schindlm","date_created":"2020-08-27T19:05:54Z","date_updated":"2020-08-30T14:34:33Z"}],"abstract":[{"text":"The cubic, tetragonal, and orthorhombic phase of potassium niobate (KNbO3) are studied based on density-functional theory. Starting from the relaxed atomic geometries, we analyze the influence of self-energy corrections on the electronic band structure within the GW approximation. We find that quasiparticle shifts widen the direct (indirect) band gap by 1.21 (1.44), 1.58 (1.55), and 1.67 (1.64) eV for the cubic, tetragonal, and orthorhombic phase, respectively. By solving the Bethe-Salpeter equation, we obtain the linear dielectric function with excitonic and local-field effects, which turn out to be essential for good agreement with experimental data. From our results, we extract an exciton binding energy of 0.6, 0.5, and 0.5 eV for the cubic, tetragonal, and orthorhombic phase, respectively. Furthermore, we investigate the nonlinear second-harmonic generation (SHG) both theoretically and experimentally. The frequency-dependent second-order polarization tensor of orthorhombic KNbO3 is measured for incoming photon energies between 1.2 and 1.6 eV. In addition, calculations within the independent-(quasi)particle approximation are performed for the tetragonal and orthorhombic phase. The novel experimental data are in excellent agreement with the quasiparticle calculations and resolve persistent discrepancies between earlier experimental measurements and ab initio results reported in the literature.","lang":"eng"}],"publication":"Physical Review Materials"},{"publication":"Journal of Physics: Materials","file":[{"content_type":"application/pdf","relation":"main_file","date_updated":"2020-08-30T14:29:27Z","date_created":"2020-08-28T09:07:18Z","creator":"schindlm","file_size":1481174,"description":"Creative Commons Attribution 3.0 Unported Public License (CC BY 3.0)","title":"Potassium titanyl phosphate (KTP) quasiparticle energies and optical response","access_level":"open_access","file_id":"18535","file_name":"Neufeld_2019_J._Phys._Mater._2_045003.pdf"}],"abstract":[{"text":"The KTiOPO4 (KTP) band structure and dielectric function are calculated on various levels of theory starting from density-functional calculations. Within the independent-particle approximation an electronic transport gap of 2.97 eV is obtained that widens to about 5.23 eV when quasiparticle effects are included using the GW approximation. The optical response is shown to be strongly anisotropic due to (i) the slight asymmetry of the TiO6 octahedra in the (001) plane and (ii) their anisotropic distribution along the [001] and [100] directions. In addition, excitonic effects are very important: The solution of the Bethe–Salpeter equation indicates exciton binding energies of the order of 1.5 eV. Calculations that include both quasiparticle and excitonic effects are in good agreement with the measured reflectivity.","lang":"eng"}],"external_id":{"isi":["000560410300003"]},"language":[{"iso":"eng"}],"ddc":["530"],"quality_controlled":"1","year":"2019","date_created":"2019-09-19T14:34:16Z","publisher":"IOP Publishing","title":"Potassium titanyl phosphate (KTP) quasiparticle energies and optical response","type":"journal_article","status":"public","user_id":"171","department":[{"_id":"296"},{"_id":"295"},{"_id":"230"},{"_id":"429"},{"_id":"170"},{"_id":"35"}],"project":[{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"name":"TRR 142","_id":"53"},{"name":"TRR 142 - Project Area B","_id":"55"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"_id":"52","name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"_id":"13365","file_date_updated":"2020-08-30T14:29:27Z","isi":"1","article_type":"original","publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["2515-7639"]},"citation":{"apa":"Neufeld, S., Bocchini, A., Gerstmann, U., Schindlmayr, A., &#38; Schmidt, W. G. (2019). Potassium titanyl phosphate (KTP) quasiparticle energies and optical response. <i>Journal of Physics: Materials</i>, <i>2</i>, 045003. <a href=\"https://doi.org/10.1088/2515-7639/ab29ba\">https://doi.org/10.1088/2515-7639/ab29ba</a>","mla":"Neufeld, Sergej, et al. “Potassium Titanyl Phosphate (KTP) Quasiparticle Energies and Optical Response.” <i>Journal of Physics: Materials</i>, vol. 2, IOP Publishing, 2019, p. 045003, doi:<a href=\"https://doi.org/10.1088/2515-7639/ab29ba\">10.1088/2515-7639/ab29ba</a>.","bibtex":"@article{Neufeld_Bocchini_Gerstmann_Schindlmayr_Schmidt_2019, title={Potassium titanyl phosphate (KTP) quasiparticle energies and optical response}, volume={2}, DOI={<a href=\"https://doi.org/10.1088/2515-7639/ab29ba\">10.1088/2515-7639/ab29ba</a>}, journal={Journal of Physics: Materials}, publisher={IOP Publishing}, author={Neufeld, Sergej and Bocchini, Adriana and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}, year={2019}, pages={045003} }","short":"S. Neufeld, A. Bocchini, U. Gerstmann, A. Schindlmayr, W.G. Schmidt, Journal of Physics: Materials 2 (2019) 045003.","chicago":"Neufeld, Sergej, Adriana Bocchini, Uwe Gerstmann, Arno Schindlmayr, and Wolf Gero Schmidt. “Potassium Titanyl Phosphate (KTP) Quasiparticle Energies and Optical Response.” <i>Journal of Physics: Materials</i> 2 (2019): 045003. <a href=\"https://doi.org/10.1088/2515-7639/ab29ba\">https://doi.org/10.1088/2515-7639/ab29ba</a>.","ieee":"S. Neufeld, A. Bocchini, U. Gerstmann, A. Schindlmayr, and W. G. Schmidt, “Potassium titanyl phosphate (KTP) quasiparticle energies and optical response,” <i>Journal of Physics: Materials</i>, vol. 2, p. 045003, 2019, doi: <a href=\"https://doi.org/10.1088/2515-7639/ab29ba\">10.1088/2515-7639/ab29ba</a>.","ama":"Neufeld S, Bocchini A, Gerstmann U, Schindlmayr A, Schmidt WG. Potassium titanyl phosphate (KTP) quasiparticle energies and optical response. <i>Journal of Physics: Materials</i>. 2019;2:045003. doi:<a href=\"https://doi.org/10.1088/2515-7639/ab29ba\">10.1088/2515-7639/ab29ba</a>"},"page":"045003","intvolume":"         2","author":[{"first_name":"Sergej","id":"23261","full_name":"Neufeld, Sergej","last_name":"Neufeld"},{"last_name":"Bocchini","orcid":"https://orcid.org/0000-0002-2134-3075","id":"58349","full_name":"Bocchini, Adriana","first_name":"Adriana"},{"first_name":"Uwe","last_name":"Gerstmann","orcid":"0000-0002-4476-223X","id":"171","full_name":"Gerstmann, Uwe"},{"last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","id":"458","full_name":"Schindlmayr, Arno","first_name":"Arno"},{"last_name":"Schmidt","orcid":"0000-0002-2717-5076","full_name":"Schmidt, Wolf Gero","id":"468","first_name":"Wolf Gero"}],"volume":2,"oa":"1","date_updated":"2023-04-21T11:36:12Z","doi":"10.1088/2515-7639/ab29ba"},{"external_id":{"isi":["000419778500006"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"Physical Review Materials","file":[{"relation":"main_file","content_type":"application/pdf","file_id":"18536","file_name":"PhysRevMaterials.2.019902.pdf","access_level":"open_access","description":"© 2018 American Physical Society","file_size":178961,"title":"Erratum: Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]","date_created":"2020-08-28T09:11:59Z","creator":"schindlm","date_updated":"2020-08-30T14:34:54Z"}],"publisher":"American Physical Society","date_created":"2019-09-20T11:28:23Z","title":"Erratum: Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]","quality_controlled":"1","issue":"1","year":"2018","project":[{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"_id":"53","name":"TRR 142"},{"_id":"55","name":"TRR 142 - Project Area B"},{"_id":"68","name":"TRR 142 - Subproject B3"},{"_id":"69","name":"TRR 142 - Subproject B4"}],"_id":"13410","user_id":"458","department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"}],"article_number":"019902","isi":"1","file_date_updated":"2020-08-30T14:34:54Z","type":"journal_article","status":"public","date_updated":"2025-12-05T10:07:07Z","oa":"1","author":[{"first_name":"Michael","full_name":"Friedrich, Michael","last_name":"Friedrich"},{"full_name":"Schmidt, Wolf Gero","id":"468","last_name":"Schmidt","orcid":"0000-0002-2717-5076","first_name":"Wolf Gero"},{"first_name":"Arno","id":"458","full_name":"Schindlmayr, Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X"},{"last_name":"Sanna","full_name":"Sanna, Simone","first_name":"Simone"}],"volume":2,"doi":"10.1103/PhysRevMaterials.2.019902","publication_status":"published","publication_identifier":{"eissn":["2475-9953"]},"has_accepted_license":"1","related_material":{"record":[{"relation":"other","id":"10021","status":"public"}]},"citation":{"mla":"Friedrich, Michael, et al. “Erratum: Optical Properties of Titanium-Doped Lithium Niobate from Time-Dependent Density-Functional Theory [Phys. Rev. Materials 1, 034401 (2017)].” <i>Physical Review Materials</i>, vol. 2, no. 1, 019902, American Physical Society, 2018, doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.2.019902\">10.1103/PhysRevMaterials.2.019902</a>.","short":"M. Friedrich, W.G. Schmidt, A. Schindlmayr, S. Sanna, Physical Review Materials 2 (2018).","bibtex":"@article{Friedrich_Schmidt_Schindlmayr_Sanna_2018, title={Erratum: Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]}, volume={2}, DOI={<a href=\"https://doi.org/10.1103/PhysRevMaterials.2.019902\">10.1103/PhysRevMaterials.2.019902</a>}, number={1019902}, journal={Physical Review Materials}, publisher={American Physical Society}, author={Friedrich, Michael and Schmidt, Wolf Gero and Schindlmayr, Arno and Sanna, Simone}, year={2018} }","apa":"Friedrich, M., Schmidt, W. G., Schindlmayr, A., &#38; Sanna, S. (2018). Erratum: Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]. <i>Physical Review Materials</i>, <i>2</i>(1). <a href=\"https://doi.org/10.1103/PhysRevMaterials.2.019902\">https://doi.org/10.1103/PhysRevMaterials.2.019902</a>","ama":"Friedrich M, Schmidt WG, Schindlmayr A, Sanna S. Erratum: Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]. <i>Physical Review Materials</i>. 2018;2(1). doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.2.019902\">10.1103/PhysRevMaterials.2.019902</a>","chicago":"Friedrich, Michael, Wolf Gero Schmidt, Arno Schindlmayr, and Simone Sanna. “Erratum: Optical Properties of Titanium-Doped Lithium Niobate from Time-Dependent Density-Functional Theory [Phys. Rev. Materials 1, 034401 (2017)].” <i>Physical Review Materials</i> 2, no. 1 (2018). <a href=\"https://doi.org/10.1103/PhysRevMaterials.2.019902\">https://doi.org/10.1103/PhysRevMaterials.2.019902</a>.","ieee":"M. Friedrich, W. G. Schmidt, A. Schindlmayr, and S. Sanna, “Erratum: Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory [Phys. Rev. Materials 1, 034401 (2017)],” <i>Physical Review Materials</i>, vol. 2, no. 1, 2018."},"intvolume":"         2"},{"year":"2018","quality_controlled":"1","title":"Exact formulation of the transverse dynamic spin susceptibility as an initial-value problem","date_created":"2020-08-27T19:18:34Z","publisher":"Hindawi","file":[{"description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"Exact formulation of the transverse dynamic spin susceptibility as an initial-value problem","file_id":"18537","access_level":"open_access","date_updated":"2020-08-30T14:31:38Z","date_created":"2020-08-28T09:18:25Z","relation":"main_file","file_size":294410,"file_name":"3732892.pdf","creator":"schindlm","content_type":"application/pdf"}],"abstract":[{"text":"The transverse dynamic spin susceptibility is a correlation function that yields exact information about spin excitations in systems with a collinear magnetic ground state, including collective spin-wave modes. In an ab initio context, it may be calculated within many-body perturbation theory or time-dependent density-functional theory, but the quantitative accuracy is currently limited by the available functionals for exchange and correlation in dynamically evolving systems. To circumvent this limitation, the spin susceptibility is here alternatively formulated as the solution of an initial-value problem. In this way, the challenge of accurately describing exchange and correlation in many-electron systems is shifted to the stationary initial state, which is much better understood. The proposed scheme further requires the choice of an auxiliary basis set, which determines the speed of convergence but always allows systematic convergence in practical implementations.","lang":"eng"}],"publication":"Advances in Mathematical Physics","language":[{"iso":"eng"}],"ddc":["530"],"external_id":{"isi":["000422773000001"]},"citation":{"ieee":"A. Schindlmayr, “Exact formulation of the transverse dynamic spin susceptibility as an initial-value problem,” <i>Advances in Mathematical Physics</i>, vol. 2018, Art. no. 3732892, 2018, doi: <a href=\"https://doi.org/10.1155/2018/3732892\">10.1155/2018/3732892</a>.","chicago":"Schindlmayr, Arno. “Exact Formulation of the Transverse Dynamic Spin Susceptibility as an Initial-Value Problem.” <i>Advances in Mathematical Physics</i> 2018 (2018). <a href=\"https://doi.org/10.1155/2018/3732892\">https://doi.org/10.1155/2018/3732892</a>.","ama":"Schindlmayr A. Exact formulation of the transverse dynamic spin susceptibility as an initial-value problem. <i>Advances in Mathematical Physics</i>. 2018;2018. doi:<a href=\"https://doi.org/10.1155/2018/3732892\">10.1155/2018/3732892</a>","mla":"Schindlmayr, Arno. “Exact Formulation of the Transverse Dynamic Spin Susceptibility as an Initial-Value Problem.” <i>Advances in Mathematical Physics</i>, vol. 2018, 3732892, Hindawi, 2018, doi:<a href=\"https://doi.org/10.1155/2018/3732892\">10.1155/2018/3732892</a>.","short":"A. Schindlmayr, Advances in Mathematical Physics 2018 (2018).","bibtex":"@article{Schindlmayr_2018, title={Exact formulation of the transverse dynamic spin susceptibility as an initial-value problem}, volume={2018}, DOI={<a href=\"https://doi.org/10.1155/2018/3732892\">10.1155/2018/3732892</a>}, number={3732892}, journal={Advances in Mathematical Physics}, publisher={Hindawi}, author={Schindlmayr, Arno}, year={2018} }","apa":"Schindlmayr, A. (2018). Exact formulation of the transverse dynamic spin susceptibility as an initial-value problem. <i>Advances in Mathematical Physics</i>, <i>2018</i>, Article 3732892. <a href=\"https://doi.org/10.1155/2018/3732892\">https://doi.org/10.1155/2018/3732892</a>"},"intvolume":"      2018","publication_status":"published","publication_identifier":{"eissn":["1687-9139"],"issn":["1687-9120"]},"has_accepted_license":"1","doi":"10.1155/2018/3732892","author":[{"orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","id":"458","full_name":"Schindlmayr, Arno","first_name":"Arno"}],"volume":2018,"oa":"1","date_updated":"2025-12-16T08:04:17Z","status":"public","type":"journal_article","file_date_updated":"2020-08-30T14:31:38Z","article_number":"3732892","article_type":"original","isi":"1","user_id":"16199","department":[{"_id":"296"},{"_id":"35"},{"_id":"15"},{"_id":"170"},{"_id":"230"}],"_id":"18466"},{"external_id":{"isi":["000394873300001"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"Advances in Materials Science and Engineering","abstract":[{"text":"We perform a comprehensive theoretical study of the structural and electronic properties of potassium niobate (KNbO3) in the cubic, tetragonal, orthorhombic, monoclinic, and rhombohedral phase, based on density-functional theory. The influence of different parametrizations of the exchange-correlation functional on the investigated properties is analyzed in detail, and the results are compared to available experimental data. We argue that the PBEsol and AM05 generalized gradient approximations as well as the RTPSS meta-generalized gradient approximation yield consistently accurate structural data for both the external and internal degrees of freedom and are overall superior to the local-density approximation or other conventional generalized gradient approximations for the structural characterization of KNbO3. Band-structure calculations using a HSE-type hybrid functional further indicate significant near degeneracies of band-edge states in all phases which are expected to be relevant for the optical response of the material.","lang":"eng"}],"file":[{"date_updated":"2020-08-30T14:37:31Z","date_created":"2020-08-28T09:27:19Z","description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"Consistent atomic geometries and electronic structure of five phases of potassium niobate from density-functional theory","file_id":"18538","access_level":"open_access","relation":"main_file","creator":"schindlm","file_size":985948,"file_name":"3981317.pdf","content_type":"application/pdf"}],"publisher":"Hindawi","date_created":"2019-05-29T07:48:32Z","title":"Consistent atomic geometries and electronic structure of five phases of potassium niobate from density-functional theory","quality_controlled":"1","year":"2017","project":[{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"_id":"53","name":"TRR 142"},{"name":"TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"_id":"10023","user_id":"16199","department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"15"},{"_id":"35"},{"_id":"27"}],"article_type":"original","article_number":"3981317","isi":"1","file_date_updated":"2020-08-30T14:37:31Z","type":"journal_article","status":"public","date_updated":"2025-12-05T09:58:11Z","oa":"1","author":[{"first_name":"Falko","full_name":"Schmidt, Falko","id":"35251","last_name":"Schmidt","orcid":"0000-0002-5071-5528"},{"last_name":"Landmann","full_name":"Landmann, Marc","first_name":"Marc"},{"first_name":"Eva","last_name":"Rauls","full_name":"Rauls, Eva"},{"full_name":"Argiolas, Nicola","last_name":"Argiolas","first_name":"Nicola"},{"first_name":"Simone","last_name":"Sanna","full_name":"Sanna, Simone"},{"first_name":"Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt","id":"468","full_name":"Schmidt, Wolf Gero"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458"}],"volume":2017,"doi":"10.1155/2017/3981317","publication_status":"published","has_accepted_license":"1","publication_identifier":{"issn":["1687-8434"],"eissn":["1687-8442"]},"citation":{"ama":"Schmidt F, Landmann M, Rauls E, et al. Consistent atomic geometries and electronic structure of five phases of potassium niobate from density-functional theory. <i>Advances in Materials Science and Engineering</i>. 2017;2017. doi:<a href=\"https://doi.org/10.1155/2017/3981317\">10.1155/2017/3981317</a>","ieee":"F. Schmidt <i>et al.</i>, “Consistent atomic geometries and electronic structure of five phases of potassium niobate from density-functional theory,” <i>Advances in Materials Science and Engineering</i>, vol. 2017, Art. no. 3981317, 2017, doi: <a href=\"https://doi.org/10.1155/2017/3981317\">10.1155/2017/3981317</a>.","chicago":"Schmidt, Falko, Marc Landmann, Eva Rauls, Nicola Argiolas, Simone Sanna, Wolf Gero Schmidt, and Arno Schindlmayr. “Consistent Atomic Geometries and Electronic Structure of Five Phases of Potassium Niobate from Density-Functional Theory.” <i>Advances in Materials Science and Engineering</i> 2017 (2017). <a href=\"https://doi.org/10.1155/2017/3981317\">https://doi.org/10.1155/2017/3981317</a>.","mla":"Schmidt, Falko, et al. “Consistent Atomic Geometries and Electronic Structure of Five Phases of Potassium Niobate from Density-Functional Theory.” <i>Advances in Materials Science and Engineering</i>, vol. 2017, 3981317, Hindawi, 2017, doi:<a href=\"https://doi.org/10.1155/2017/3981317\">10.1155/2017/3981317</a>.","short":"F. Schmidt, M. Landmann, E. Rauls, N. Argiolas, S. Sanna, W.G. Schmidt, A. Schindlmayr, Advances in Materials Science and Engineering 2017 (2017).","bibtex":"@article{Schmidt_Landmann_Rauls_Argiolas_Sanna_Schmidt_Schindlmayr_2017, title={Consistent atomic geometries and electronic structure of five phases of potassium niobate from density-functional theory}, volume={2017}, DOI={<a href=\"https://doi.org/10.1155/2017/3981317\">10.1155/2017/3981317</a>}, number={3981317}, journal={Advances in Materials Science and Engineering}, publisher={Hindawi}, author={Schmidt, Falko and Landmann, Marc and Rauls, Eva and Argiolas, Nicola and Sanna, Simone and Schmidt, Wolf Gero and Schindlmayr, Arno}, year={2017} }","apa":"Schmidt, F., Landmann, M., Rauls, E., Argiolas, N., Sanna, S., Schmidt, W. G., &#38; Schindlmayr, A. (2017). Consistent atomic geometries and electronic structure of five phases of potassium niobate from density-functional theory. <i>Advances in Materials Science and Engineering</i>, <i>2017</i>, Article 3981317. <a href=\"https://doi.org/10.1155/2017/3981317\">https://doi.org/10.1155/2017/3981317</a>"},"intvolume":"      2017"},{"issue":"3","quality_controlled":"1","year":"2017","date_created":"2019-05-29T07:42:33Z","publisher":"American Physical Society","title":"Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory","publication":"Physical Review Materials","file":[{"content_type":"application/pdf","creator":"schindlm","file_size":708075,"file_name":"PhysRevMaterials.1.034401.pdf","relation":"main_file","date_updated":"2020-08-30T14:36:11Z","date_created":"2020-08-27T19:39:54Z","title":"Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory","description":"© 2017 American Physical Society","file_id":"18467","access_level":"open_access"}],"abstract":[{"text":"The optical properties of pristine and titanium-doped LiNbO3 are modeled from first principles. The dielectric functions are calculated within time-dependent density-functional theory, and a model long-range contribution is employed for the exchange-correlation kernel in order to account for the electron-hole binding. Our study focuses on the influence of substitutional titanium atoms on lithium sites. We show that an increasing titanium concentration enhances the values of the refractive indices and the reflectivity.","lang":"eng"}],"external_id":{"isi":["000416562300001"]},"language":[{"iso":"eng"}],"ddc":["530"],"related_material":{"record":[{"id":"13410","relation":"other","status":"public"}]},"publication_status":"published","has_accepted_license":"1","publication_identifier":{"issn":["2475-9953"]},"citation":{"mla":"Friedrich, Michael, et al. “Optical Properties of Titanium-Doped Lithium Niobate from Time-Dependent Density-Functional Theory.” <i>Physical Review Materials</i>, vol. 1, no. 3, 034401, American Physical Society, 2017, doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.1.034401\">10.1103/PhysRevMaterials.1.034401</a>.","short":"M. Friedrich, W.G. Schmidt, A. Schindlmayr, S. Sanna, Physical Review Materials 1 (2017).","bibtex":"@article{Friedrich_Schmidt_Schindlmayr_Sanna_2017, title={Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory}, volume={1}, DOI={<a href=\"https://doi.org/10.1103/PhysRevMaterials.1.034401\">10.1103/PhysRevMaterials.1.034401</a>}, number={3034401}, journal={Physical Review Materials}, publisher={American Physical Society}, author={Friedrich, Michael and Schmidt, Wolf Gero and Schindlmayr, Arno and Sanna, Simone}, year={2017} }","apa":"Friedrich, M., Schmidt, W. G., Schindlmayr, A., &#38; Sanna, S. (2017). Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory. <i>Physical Review Materials</i>, <i>1</i>(3), Article 034401. <a href=\"https://doi.org/10.1103/PhysRevMaterials.1.034401\">https://doi.org/10.1103/PhysRevMaterials.1.034401</a>","ama":"Friedrich M, Schmidt WG, Schindlmayr A, Sanna S. Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory. <i>Physical Review Materials</i>. 2017;1(3). doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.1.034401\">10.1103/PhysRevMaterials.1.034401</a>","ieee":"M. Friedrich, W. G. Schmidt, A. Schindlmayr, and S. Sanna, “Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory,” <i>Physical Review Materials</i>, vol. 1, no. 3, Art. no. 034401, 2017, doi: <a href=\"https://doi.org/10.1103/PhysRevMaterials.1.034401\">10.1103/PhysRevMaterials.1.034401</a>.","chicago":"Friedrich, Michael, Wolf Gero Schmidt, Arno Schindlmayr, and Simone Sanna. “Optical Properties of Titanium-Doped Lithium Niobate from Time-Dependent Density-Functional Theory.” <i>Physical Review Materials</i> 1, no. 3 (2017). <a href=\"https://doi.org/10.1103/PhysRevMaterials.1.034401\">https://doi.org/10.1103/PhysRevMaterials.1.034401</a>."},"intvolume":"         1","author":[{"first_name":"Michael","full_name":"Friedrich, Michael","last_name":"Friedrich"},{"first_name":"Wolf Gero","full_name":"Schmidt, Wolf Gero","id":"468","last_name":"Schmidt","orcid":"0000-0002-2717-5076"},{"id":"458","full_name":"Schindlmayr, Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","first_name":"Arno"},{"full_name":"Sanna, Simone","last_name":"Sanna","first_name":"Simone"}],"volume":1,"oa":"1","date_updated":"2025-12-05T10:07:07Z","doi":"10.1103/PhysRevMaterials.1.034401","type":"journal_article","status":"public","user_id":"16199","department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"35"},{"_id":"27"}],"project":[{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"name":"TRR 142","_id":"53"},{"name":"TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"name":"TRR 142 - Subproject B3","_id":"68"}],"_id":"10021","file_date_updated":"2020-08-30T14:36:11Z","article_number":"034401","isi":"1","article_type":"original"},{"year":"2017","issue":"5","quality_controlled":"1","title":"Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory","date_created":"2019-09-20T11:54:25Z","publisher":"American Physical Society","file":[{"creator":"schindlm","date_created":"2020-08-27T19:43:49Z","date_updated":"2020-08-30T14:38:50Z","file_name":"PhysRevMaterials.1.054406.pdf","file_id":"18468","access_level":"open_access","title":"Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory","description":"© 2017 American Physical Society","file_size":1417182,"content_type":"application/pdf","relation":"main_file"}],"abstract":[{"lang":"eng","text":"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."}],"publication":"Physical Review Materials","language":[{"iso":"eng"}],"ddc":["530"],"external_id":{"isi":["000416586100003"]},"intvolume":"         1","citation":{"mla":"Friedrich, Michael, et al. “Polaron Optical Absorption in Congruent Lithium Niobate from Time-Dependent Density-Functional Theory.” <i>Physical Review Materials</i>, vol. 1, no. 5, 054406, American Physical Society, 2017, doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.1.054406\">10.1103/PhysRevMaterials.1.054406</a>.","short":"M. Friedrich, W.G. Schmidt, A. Schindlmayr, S. Sanna, Physical Review Materials 1 (2017).","bibtex":"@article{Friedrich_Schmidt_Schindlmayr_Sanna_2017, title={Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory}, volume={1}, DOI={<a href=\"https://doi.org/10.1103/PhysRevMaterials.1.054406\">10.1103/PhysRevMaterials.1.054406</a>}, 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} }","apa":"Friedrich, M., Schmidt, W. G., Schindlmayr, A., &#38; Sanna, S. (2017). Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory. <i>Physical Review Materials</i>, <i>1</i>(5), Article 054406. <a href=\"https://doi.org/10.1103/PhysRevMaterials.1.054406\">https://doi.org/10.1103/PhysRevMaterials.1.054406</a>","chicago":"Friedrich, Michael, Wolf Gero Schmidt, Arno Schindlmayr, and Simone Sanna. “Polaron Optical Absorption in Congruent Lithium Niobate from Time-Dependent Density-Functional Theory.” <i>Physical Review Materials</i> 1, no. 5 (2017). <a href=\"https://doi.org/10.1103/PhysRevMaterials.1.054406\">https://doi.org/10.1103/PhysRevMaterials.1.054406</a>.","ieee":"M. Friedrich, W. G. Schmidt, A. Schindlmayr, and S. Sanna, “Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory,” <i>Physical Review Materials</i>, vol. 1, no. 5, Art. no. 054406, 2017, doi: <a href=\"https://doi.org/10.1103/PhysRevMaterials.1.054406\">10.1103/PhysRevMaterials.1.054406</a>.","ama":"Friedrich M, Schmidt WG, Schindlmayr A, Sanna S. Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory. <i>Physical Review Materials</i>. 2017;1(5). doi:<a href=\"https://doi.org/10.1103/PhysRevMaterials.1.054406\">10.1103/PhysRevMaterials.1.054406</a>"},"publication_identifier":{"eissn":["2475-9953"]},"has_accepted_license":"1","publication_status":"published","doi":"10.1103/PhysRevMaterials.1.054406","volume":1,"author":[{"first_name":"Michael","full_name":"Friedrich, Michael","last_name":"Friedrich"},{"full_name":"Schmidt, Wolf Gero","id":"468","last_name":"Schmidt","orcid":"0000-0002-2717-5076","first_name":"Wolf Gero"},{"full_name":"Schindlmayr, Arno","id":"458","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","first_name":"Arno"},{"first_name":"Simone","last_name":"Sanna","full_name":"Sanna, Simone"}],"oa":"1","date_updated":"2025-12-05T10:14:23Z","status":"public","type":"journal_article","file_date_updated":"2020-08-30T14:38:50Z","isi":"1","article_number":"054406","article_type":"original","department":[{"_id":"296"},{"_id":"295"},{"_id":"230"},{"_id":"429"},{"_id":"35"},{"_id":"15"},{"_id":"27"}],"user_id":"16199","_id":"13416","project":[{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"_id":"53","name":"TRR 142"},{"name":"TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - Subproject B3","_id":"68"},{"name":"TRR 142 - Subproject B4","_id":"69"}]},{"type":"journal_article","status":"public","project":[{"name":"TRR 142","_id":"53"},{"name":"TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - Subproject B1","_id":"66"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"_id":"7481","user_id":"16199","department":[{"_id":"287"},{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"35"},{"_id":"15"},{"_id":"170"},{"_id":"429"},{"_id":"27"}],"article_type":"original","isi":"1","article_number":"215702","file_date_updated":"2020-08-30T14:34:08Z","publication_status":"published","publication_identifier":{"eissn":["1361-648X"],"issn":["0953-8984"]},"has_accepted_license":"1","pmid":"1","citation":{"bibtex":"@article{Riefer_Weber_Mund_Yakovlev_Bayer_Schindlmayr_Meier_Schmidt_2017, title={Zn–VI quasiparticle gaps and optical spectra from many-body calculations}, volume={29}, DOI={<a href=\"https://doi.org/10.1088/1361-648x/aa6b2a\">10.1088/1361-648x/aa6b2a</a>}, number={21215702}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Riefer, Arthur and Weber, Nils and Mund, Johannes and Yakovlev, Dmitri R. and Bayer, Manfred and Schindlmayr, Arno and Meier, Cedrik and Schmidt, Wolf Gero}, year={2017} }","mla":"Riefer, Arthur, et al. “Zn–VI Quasiparticle Gaps and Optical Spectra from Many-Body Calculations.” <i>Journal of Physics: Condensed Matter</i>, vol. 29, no. 21, 215702, IOP Publishing, 2017, doi:<a href=\"https://doi.org/10.1088/1361-648x/aa6b2a\">10.1088/1361-648x/aa6b2a</a>.","short":"A. Riefer, N. Weber, J. Mund, D.R. Yakovlev, M. Bayer, A. Schindlmayr, C. Meier, W.G. Schmidt, Journal of Physics: Condensed Matter 29 (2017).","apa":"Riefer, A., Weber, N., Mund, J., Yakovlev, D. R., Bayer, M., Schindlmayr, A., Meier, C., &#38; Schmidt, W. G. (2017). Zn–VI quasiparticle gaps and optical spectra from many-body calculations. <i>Journal of Physics: Condensed Matter</i>, <i>29</i>(21), Article 215702. <a href=\"https://doi.org/10.1088/1361-648x/aa6b2a\">https://doi.org/10.1088/1361-648x/aa6b2a</a>","ama":"Riefer A, Weber N, Mund J, et al. Zn–VI quasiparticle gaps and optical spectra from many-body calculations. <i>Journal of Physics: Condensed Matter</i>. 2017;29(21). doi:<a href=\"https://doi.org/10.1088/1361-648x/aa6b2a\">10.1088/1361-648x/aa6b2a</a>","ieee":"A. Riefer <i>et al.</i>, “Zn–VI quasiparticle gaps and optical spectra from many-body calculations,” <i>Journal of Physics: Condensed Matter</i>, vol. 29, no. 21, Art. no. 215702, 2017, doi: <a href=\"https://doi.org/10.1088/1361-648x/aa6b2a\">10.1088/1361-648x/aa6b2a</a>.","chicago":"Riefer, Arthur, Nils Weber, Johannes Mund, Dmitri R. Yakovlev, Manfred Bayer, Arno Schindlmayr, Cedrik Meier, and Wolf Gero Schmidt. “Zn–VI Quasiparticle Gaps and Optical Spectra from Many-Body Calculations.” <i>Journal of Physics: Condensed Matter</i> 29, no. 21 (2017). <a href=\"https://doi.org/10.1088/1361-648x/aa6b2a\">https://doi.org/10.1088/1361-648x/aa6b2a</a>."},"intvolume":"        29","date_updated":"2025-12-16T11:07:33Z","author":[{"first_name":"Arthur","full_name":"Riefer, Arthur","last_name":"Riefer"},{"first_name":"Nils","last_name":"Weber","full_name":"Weber, Nils"},{"last_name":"Mund","full_name":"Mund, Johannes","first_name":"Johannes"},{"last_name":"Yakovlev","full_name":"Yakovlev, Dmitri R.","first_name":"Dmitri R."},{"first_name":"Manfred","last_name":"Bayer","full_name":"Bayer, Manfred"},{"orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458","first_name":"Arno"},{"last_name":"Meier","orcid":"https://orcid.org/0000-0002-3787-3572","full_name":"Meier, Cedrik","id":"20798","first_name":"Cedrik"},{"first_name":"Wolf Gero","full_name":"Schmidt, Wolf Gero","id":"468","orcid":"0000-0002-2717-5076","last_name":"Schmidt"}],"volume":29,"doi":"10.1088/1361-648x/aa6b2a","publication":"Journal of Physics: Condensed Matter","abstract":[{"text":"The electronic band structures of hexagonal ZnO and cubic ZnS, ZnSe, and ZnTe compounds are determined within hybrid-density-functional theory and quasiparticle calculations. It is found that the band-edge energies calculated on the G0W0 (Zn chalcogenides) or GW (ZnO) level of theory agree well with experiment, while fully self-consistent QSGW calculations are required for the correct description of the Zn 3d bands. The quasiparticle band structures are used to calculate the linear response and second-harmonic-generation (SHG) spectra of the Zn–VI compounds. Excitonic effects in the optical absorption are accounted for within the Bethe–Salpeter approach. The calculated spectra are discussed in the context of previous experimental data and present SHG measurements for ZnO.","lang":"eng"}],"file":[{"access_level":"closed","file_name":"Riefer_2017_J._Phys. _Condens._Matter_29_215702.pdf","file_id":"18574","title":"Zn–VI quasiparticle gaps and optical spectra from many-body calculations","file_size":2551657,"description":"© 2017 IOP Publishing Ltd","creator":"schindlm","date_created":"2020-08-28T14:01:15Z","date_updated":"2020-08-30T14:34:08Z","relation":"main_file","content_type":"application/pdf"}],"external_id":{"pmid":["28374685"],"isi":["000400093100001"]},"ddc":["530"],"language":[{"iso":"eng"}],"quality_controlled":"1","issue":"21","year":"2017","publisher":"IOP Publishing","date_created":"2019-02-04T13:46:58Z","title":"Zn–VI quasiparticle gaps and optical spectra from many-body calculations"}]