[{"status":"public","type":"journal_article","article_number":"1586","article_type":"original","isi":"1","file_date_updated":"2023-06-12T00:22:51Z","_id":"44088","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"},{"_id":"166","name":"TRR 142 - A11: TRR 142 - Subproject A11"},{"_id":"52","name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"department":[{"_id":"15"},{"_id":"296"},{"_id":"170"},{"_id":"295"},{"_id":"35"},{"_id":"230"},{"_id":"429"},{"_id":"27"}],"user_id":"16199","intvolume":"        12","citation":{"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>","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>.","short":"F. Schmidt, A.L. Kozub, U. Gerstmann, W.G. Schmidt, A. Schindlmayr, Crystals 12 (2022).","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>.","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} }","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>"},"publication_identifier":{"eissn":["2073-4352"]},"has_accepted_license":"1","publication_status":"published","doi":"10.3390/cryst12111586","date_updated":"2025-09-18T13:28:05Z","oa":"1","volume":12,"author":[{"first_name":"Falko","id":"35251","full_name":"Schmidt, Falko","last_name":"Schmidt","orcid":"0000-0002-5071-5528"},{"first_name":"Agnieszka L.","id":"77566","full_name":"Kozub, Agnieszka L.","orcid":"0000-0001-6584-0201","last_name":"Kozub"},{"first_name":"Uwe","id":"171","full_name":"Gerstmann, Uwe","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"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","id":"458","full_name":"Schindlmayr, Arno"}],"abstract":[{"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.","lang":"eng"}],"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","access_level":"open_access","file_id":"45570","file_name":"crystals-12-01586-v2.pdf","date_updated":"2023-06-12T00:22:51Z","date_created":"2023-06-11T23:59:27Z","creator":"schindlm"}],"publication":"Crystals","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000895837200001"]},"year":"2022","quality_controlled":"1","issue":"11","title":"A density-functional theory study of hole and defect-bound exciton polarons in lithium niobate","publisher":"MDPI AG","date_created":"2023-04-20T13:52:44Z"},{"place":"Basel","citation":{"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>","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>.","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.","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.","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} }","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>"},"page":"231-248","publication_status":"published","publication_identifier":{"isbn":["978-3-0365-3340-7"],"eisbn":["978-3-0365-3339-1"]},"doi":"10.3390/books978-3-0365-3339-1","date_updated":"2025-12-05T14:00:04Z","author":[{"first_name":"Falko","orcid":"0000-0002-5071-5528","last_name":"Schmidt","full_name":"Schmidt, Falko","id":"35251"},{"last_name":"Kozub","orcid":"https://orcid.org/0000-0001-6584-0201","id":"77566","full_name":"Kozub, Agnieszka L.","first_name":"Agnieszka L."},{"orcid":"0000-0002-4476-223X","last_name":"Gerstmann","id":"171","full_name":"Gerstmann, Uwe","first_name":"Uwe"},{"last_name":"Schmidt","orcid":"0000-0002-2717-5076","id":"468","full_name":"Schmidt, Wolf Gero","first_name":"Wolf Gero"},{"full_name":"Schindlmayr, Arno","id":"458","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","first_name":"Arno"}],"editor":[{"last_name":"Corradi","full_name":"Corradi, Gábor","first_name":"Gábor"},{"first_name":"László","last_name":"Kovács","full_name":"Kovács, László"}],"status":"public","type":"book_chapter","project":[{"_id":"53","name":"TRR 142: TRR 142"},{"name":"TRR 142 - B: TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - B4: TRR 142 - Subproject B4","_id":"69"},{"name":"TRR 142 - A: TRR 142 - Project Area A","_id":"54"},{"_id":"166","name":"TRR 142 - A11: TRR 142 - Subproject A11"},{"_id":"168","name":"TRR 142 - B07: TRR 142 - Subproject B07"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"_id":"53","name":"TRR 142: Maßgeschneiderte nichtlineare Photonik: Von grundlegenden Konzepten zu funktionellen Strukturen"}],"_id":"30288","user_id":"16199","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"15"},{"_id":"170"},{"_id":"35"},{"_id":"790"}],"year":"2022","quality_controlled":"1","title":"Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response","publisher":"MDPI","date_created":"2022-03-13T15:28:47Z","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":"New Trends in Lithium Niobate: From Bulk to Nanocrystals","ddc":["530"],"language":[{"iso":"eng"}]},{"type":"journal_article","status":"public","project":[{"_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"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"_id":"21946","user_id":"171","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"15"},{"_id":"170"},{"_id":"35"},{"_id":"790"}],"isi":"1","article_type":"original","funded_apc":"1","file_date_updated":"2021-05-13T16:51:41Z","publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["2073-4352"]},"citation":{"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>.","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>","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>."},"page":"542","intvolume":"        11","date_updated":"2023-04-21T11:20:15Z","oa":"1","author":[{"full_name":"Schmidt, Falko","id":"35251","last_name":"Schmidt","orcid":"0000-0002-5071-5528","first_name":"Falko"},{"first_name":"Agnieszka L.","orcid":"https://orcid.org/0000-0001-6584-0201","last_name":"Kozub","id":"77566","full_name":"Kozub, Agnieszka L."},{"first_name":"Uwe","id":"171","full_name":"Gerstmann, Uwe","orcid":"0000-0002-4476-223X","last_name":"Gerstmann"},{"first_name":"Wolf Gero","id":"468","full_name":"Schmidt, Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt"},{"id":"458","full_name":"Schindlmayr, Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","first_name":"Arno"}],"volume":11,"doi":"10.3390/cryst11050542","publication":"Crystals","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."}],"file":[{"creator":"schindlm","date_created":"2021-05-13T16:47:11Z","date_updated":"2021-05-13T16:51:41Z","access_level":"open_access","file_id":"22163","file_name":"crystals-11-00542.pdf","title":"Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response","description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","file_size":3042827,"content_type":"application/pdf","relation":"main_file"}],"external_id":{"isi":["000653822700001"]},"ddc":["530"],"language":[{"iso":"eng"}],"quality_controlled":"1","year":"2021","publisher":"MDPI","date_created":"2021-05-03T09:36:13Z","title":"Electron polarons in lithium niobate: Charge localization, lattice deformation, and optical response"},{"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","orcid":"0000-0002-5071-5528","last_name":"Schmidt"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458"}],"volume":94,"citation":{"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} }","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>.","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>","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>","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>.","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>."},"intvolume":"        94","publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["1434-6036"],"issn":["1434-6028"]},"isi":"1","article_number":"169","article_type":"original","file_date_updated":"2021-09-02T08:05:06Z","project":[{"_id":"53","name":"TRR 142"},{"_id":"55","name":"TRR 142 - Project Area B"},{"_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"}],"status":"public","type":"journal_article","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","year":"2021","quality_controlled":"1","issue":"8","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000687163200002"]},"abstract":[{"lang":"eng","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."}],"file":[{"content_type":"application/pdf","file_size":850389,"file_name":"BidaraguppeRamesh2021_Article_LatticeParametersAndElectronic.pdf","creator":"schindlm","relation":"main_file","description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","title":"Lattice parameters and electronic bandgap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3 from density-functional theory","access_level":"open_access","file_id":"23679","date_updated":"2021-09-02T08:05:06Z","date_created":"2021-09-02T08:05:06Z"}],"publication":"The European Physical Journal B"},{"language":[{"iso":"eng"}],"ddc":["530"],"external_id":{"isi":["000671587300006"]},"file":[{"file_size":180926,"file_name":"PhysRevB.104.039901.pdf","creator":"schindlm","content_type":"application/pdf","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","relation":"main_file"}],"publication":"Physical Review B","title":"Erratum: Efficient implementation of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81, 125102 (2010)]","date_created":"2021-07-15T19:59:00Z","publisher":"American Physical Society","year":"2021","issue":"3","quality_controlled":"1","file_date_updated":"2021-07-15T20:16:55Z","article_number":"039901","isi":"1","department":[{"_id":"296"},{"_id":"15"},{"_id":"170"}],"user_id":"16199","_id":"22761","status":"public","type":"journal_article","doi":"10.1103/PhysRevB.104.039901","volume":104,"author":[{"full_name":"Friedrich, Christoph","last_name":"Friedrich","first_name":"Christoph"},{"last_name":"Blügel","full_name":"Blügel, Stefan","first_name":"Stefan"},{"id":"458","full_name":"Schindlmayr, Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","first_name":"Arno"}],"date_updated":"2023-04-20T14:57:09Z","oa":"1","intvolume":"       104","citation":{"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>","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>.","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>.","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>","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>.","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)."},"related_material":{"record":[{"relation":"other","id":"18558","status":"public"}]},"has_accepted_license":"1","publication_identifier":{"eissn":["2469-9969"],"issn":["2469-9950"]},"publication_status":"published"},{"quality_controlled":"1","year":"2021","publisher":"American Physical Society","date_created":"2021-08-16T19:09:46Z","title":"Polaronic enhancement of second-harmonic generation in lithium niobate","publication":"Physical Review B","abstract":[{"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.","lang":"eng"}],"file":[{"relation":"main_file","title":"Polaronic enhancement of second-harmonic generation in lithium niobate","description":"© 2021 American Physical Society","file_id":"27577","access_level":"open_access","date_updated":"2021-11-18T20:49:19Z","date_created":"2021-11-18T20:49:19Z","content_type":"application/pdf","file_size":804012,"file_name":"PhysRevB.104.174110.pdf","creator":"schindlm"}],"external_id":{"arxiv":["2106.01145"],"isi":["000720931400007"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication_status":"published","publication_identifier":{"eissn":["2469-9969"],"issn":["2469-9950"]},"has_accepted_license":"1","citation":{"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>","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>.","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>.","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>.","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>"},"intvolume":"       104","page":"174110","oa":"1","date_updated":"2023-04-21T11:15:30Z","author":[{"last_name":"Kozub","orcid":"https://orcid.org/0000-0001-6584-0201","id":"77566","full_name":"Kozub, Agnieszka L.","first_name":"Agnieszka L."},{"id":"458","full_name":"Schindlmayr, Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","first_name":"Arno"},{"orcid":"0000-0002-4476-223X","last_name":"Gerstmann","full_name":"Gerstmann, Uwe","id":"171","first_name":"Uwe"},{"full_name":"Schmidt, Wolf Gero","id":"468","last_name":"Schmidt","orcid":"0000-0002-2717-5076","first_name":"Wolf Gero"}],"volume":104,"doi":"10.1103/PhysRevB.104.174110","type":"journal_article","status":"public","project":[{"_id":"53","name":"TRR 142"},{"name":"TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"_id":"23418","user_id":"171","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"15"},{"_id":"170"},{"_id":"790"}],"isi":"1","article_type":"original","file_date_updated":"2021-11-18T20:49:19Z"},{"language":[{"iso":"eng"}],"ddc":["530"],"external_id":{"isi":["000604206300002"]},"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"}],"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."}],"publication":"Physical Review Research","title":"Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations","date_created":"2020-09-09T09:35:21Z","publisher":"American Physical Society","year":"2020","issue":"4","quality_controlled":"1","file_date_updated":"2020-10-02T07:37:24Z","article_type":"original","isi":"1","article_number":"043002","department":[{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"295"},{"_id":"288"},{"_id":"15"},{"_id":"170"},{"_id":"35"},{"_id":"790"}],"user_id":"16199","_id":"19190","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"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"status":"public","type":"journal_article","doi":"10.1103/PhysRevResearch.2.043002","volume":2,"author":[{"orcid":"0000-0002-5071-5528","last_name":"Schmidt","id":"35251","full_name":"Schmidt, Falko","first_name":"Falko"},{"first_name":"Agnieszka L.","orcid":"https://orcid.org/0000-0001-6584-0201","last_name":"Kozub","id":"77566","full_name":"Kozub, Agnieszka L."},{"last_name":"Biktagirov","full_name":"Biktagirov, Timur","id":"65612","first_name":"Timur"},{"first_name":"Christof","full_name":"Eigner, Christof","id":"13244","last_name":"Eigner","orcid":"https://orcid.org/0000-0002-5693-3083"},{"id":"26263","full_name":"Silberhorn, Christine","last_name":"Silberhorn","first_name":"Christine"},{"first_name":"Arno","id":"458","full_name":"Schindlmayr, Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr"},{"last_name":"Schmidt","orcid":"0000-0002-2717-5076","id":"468","full_name":"Schmidt, Wolf Gero","first_name":"Wolf Gero"},{"first_name":"Uwe","full_name":"Gerstmann, Uwe","id":"171","orcid":"0000-0002-4476-223X","last_name":"Gerstmann"}],"oa":"1","date_updated":"2023-04-20T16:06:21Z","intvolume":"         2","citation":{"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} }","short":"F. Schmidt, A.L. Kozub, T. Biktagirov, C. Eigner, C. Silberhorn, A. Schindlmayr, W.G. Schmidt, U. Gerstmann, Physical Review Research 2 (2020).","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>.","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>","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>","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>."},"publication_identifier":{"eissn":["2643-1564"]},"has_accepted_license":"1","publication_status":"published"},{"_id":"10014","project":[{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"_id":"53","name":"TRR 142"},{"name":"TRR 142 - Project Area B","_id":"55"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"170"},{"_id":"35"}],"user_id":"16199","article_type":"original","article_number":"054401","isi":"1","file_date_updated":"2020-08-30T14:34:33Z","type":"journal_article","status":"public","date_updated":"2023-04-20T14:20:33Z","oa":"1","volume":3,"author":[{"orcid":"0000-0002-5071-5528","last_name":"Schmidt","full_name":"Schmidt, Falko","id":"35251","first_name":"Falko"},{"first_name":"Arthur","last_name":"Riefer","full_name":"Riefer, Arthur"},{"last_name":"Schmidt","orcid":"0000-0002-2717-5076","id":"468","full_name":"Schmidt, Wolf Gero","first_name":"Wolf Gero"},{"orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458","first_name":"Arno"},{"first_name":"Mirco","full_name":"Imlau, Mirco","last_name":"Imlau"},{"full_name":"Dobener, Florian","last_name":"Dobener","first_name":"Florian"},{"first_name":"Nils","full_name":"Mengel, Nils","last_name":"Mengel"},{"first_name":"Sangam","last_name":"Chatterjee","full_name":"Chatterjee, Sangam"},{"first_name":"Simone","last_name":"Sanna","full_name":"Sanna, Simone"}],"doi":"10.1103/PhysRevMaterials.3.054401","has_accepted_license":"1","publication_identifier":{"eissn":["2475-9953"]},"publication_status":"published","intvolume":"         3","citation":{"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>.","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).","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} }","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>."},"external_id":{"isi":["000467044000003"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"Physical Review Materials","abstract":[{"lang":"eng","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."}],"file":[{"relation":"main_file","content_type":"application/pdf","access_level":"open_access","file_name":"PhysRevMaterials.3.054401.pdf","file_id":"18465","description":"© 2019 American Physical Society","file_size":1949504,"title":"Quasiparticle and excitonic effects in the optical response of KNbO3","date_created":"2020-08-27T19:05:54Z","creator":"schindlm","date_updated":"2020-08-30T14:34:33Z"}],"publisher":"American Physical Society","date_created":"2019-05-29T06:55:29Z","title":"Quasiparticle and excitonic effects in the optical response of KNbO3","quality_controlled":"1","issue":"5","year":"2019"},{"status":"public","type":"journal_article","isi":"1","article_type":"original","file_date_updated":"2020-08-30T14:29:27Z","_id":"13365","project":[{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"name":"TRR 142","_id":"53"},{"_id":"55","name":"TRR 142 - Project Area B"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"name":"PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"department":[{"_id":"296"},{"_id":"295"},{"_id":"230"},{"_id":"429"},{"_id":"170"},{"_id":"35"}],"user_id":"171","intvolume":"         2","page":"045003","citation":{"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} }","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>.","short":"S. Neufeld, A. Bocchini, U. Gerstmann, A. Schindlmayr, W.G. Schmidt, Journal of Physics: Materials 2 (2019) 045003.","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>","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>"},"publication_identifier":{"eissn":["2515-7639"]},"has_accepted_license":"1","publication_status":"published","doi":"10.1088/2515-7639/ab29ba","date_updated":"2023-04-21T11:36:12Z","oa":"1","volume":2,"author":[{"id":"23261","full_name":"Neufeld, Sergej","last_name":"Neufeld","first_name":"Sergej"},{"first_name":"Adriana","orcid":"https://orcid.org/0000-0002-2134-3075","last_name":"Bocchini","id":"58349","full_name":"Bocchini, Adriana"},{"first_name":"Uwe","full_name":"Gerstmann, Uwe","id":"171","orcid":"0000-0002-4476-223X","last_name":"Gerstmann"},{"orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458","first_name":"Arno"},{"id":"468","full_name":"Schmidt, Wolf Gero","last_name":"Schmidt","orcid":"0000-0002-2717-5076","first_name":"Wolf Gero"}],"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"}],"file":[{"relation":"main_file","content_type":"application/pdf","file_name":"Neufeld_2019_J._Phys._Mater._2_045003.pdf","access_level":"open_access","file_id":"18535","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","date_created":"2020-08-28T09:07:18Z","creator":"schindlm","date_updated":"2020-08-30T14:29:27Z"}],"publication":"Journal of Physics: Materials","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000560410300003"]},"year":"2019","quality_controlled":"1","title":"Potassium titanyl phosphate (KTP) quasiparticle energies and optical response","publisher":"IOP Publishing","date_created":"2019-09-19T14:34:16Z"},{"publication":"Physical Review Materials","file":[{"date_updated":"2020-08-30T14:34:54Z","creator":"schindlm","date_created":"2020-08-28T09:11:59Z","title":"Erratum: Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]","description":"© 2018 American Physical Society","file_size":178961,"access_level":"open_access","file_id":"18536","file_name":"PhysRevMaterials.2.019902.pdf","content_type":"application/pdf","relation":"main_file"}],"external_id":{"isi":["000419778500006"]},"ddc":["530"],"language":[{"iso":"eng"}],"quality_controlled":"1","issue":"1","year":"2018","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)]","type":"journal_article","status":"public","_id":"13410","project":[{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"_id":"53","name":"TRR 142"},{"name":"TRR 142 - Project Area B","_id":"55"},{"_id":"68","name":"TRR 142 - Subproject B3"},{"_id":"69","name":"TRR 142 - Subproject B4"}],"department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"}],"user_id":"458","isi":"1","article_number":"019902","file_date_updated":"2020-08-30T14:34:54Z","has_accepted_license":"1","publication_identifier":{"eissn":["2475-9953"]},"publication_status":"published","related_material":{"record":[{"id":"10021","relation":"other","status":"public"}]},"intvolume":"         2","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>","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.","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>"},"date_updated":"2025-12-05T10:07:07Z","oa":"1","volume":2,"author":[{"first_name":"Michael","last_name":"Friedrich","full_name":"Friedrich, Michael"},{"first_name":"Wolf Gero","full_name":"Schmidt, Wolf Gero","id":"468","orcid":"0000-0002-2717-5076","last_name":"Schmidt"},{"full_name":"Schindlmayr, Arno","id":"458","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","first_name":"Arno"},{"full_name":"Sanna, Simone","last_name":"Sanna","first_name":"Simone"}],"doi":"10.1103/PhysRevMaterials.2.019902"},{"title":"Exact formulation of the transverse dynamic spin susceptibility as an initial-value problem","publisher":"Hindawi","date_created":"2020-08-27T19:18:34Z","year":"2018","quality_controlled":"1","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000422773000001"]},"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"}],"file":[{"file_name":"3732892.pdf","file_size":294410,"creator":"schindlm","content_type":"application/pdf","access_level":"open_access","file_id":"18537","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","date_created":"2020-08-28T09:18:25Z","date_updated":"2020-08-30T14:31:38Z","relation":"main_file"}],"publication":"Advances in Mathematical Physics","doi":"10.1155/2018/3732892","date_updated":"2025-12-16T08:04:17Z","oa":"1","volume":2018,"author":[{"full_name":"Schindlmayr, Arno","id":"458","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","first_name":"Arno"}],"intvolume":"      2018","citation":{"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>","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>.","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>.","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} }","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>.","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>"},"publication_identifier":{"eissn":["1687-9139"],"issn":["1687-9120"]},"has_accepted_license":"1","publication_status":"published","article_type":"original","isi":"1","article_number":"3732892","file_date_updated":"2020-08-30T14:31:38Z","_id":"18466","department":[{"_id":"296"},{"_id":"35"},{"_id":"15"},{"_id":"170"},{"_id":"230"}],"user_id":"16199","status":"public","type":"journal_article"},{"has_accepted_license":"1","publication_identifier":{"issn":["1687-8434"],"eissn":["1687-8442"]},"publication_status":"published","intvolume":"      2017","citation":{"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} }","short":"F. Schmidt, M. Landmann, E. Rauls, N. Argiolas, S. Sanna, W.G. Schmidt, A. Schindlmayr, Advances in Materials Science and Engineering 2017 (2017).","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>.","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>","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>","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>.","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>."},"date_updated":"2025-12-05T09:58:11Z","oa":"1","volume":2017,"author":[{"first_name":"Falko","id":"35251","full_name":"Schmidt, Falko","last_name":"Schmidt","orcid":"0000-0002-5071-5528"},{"last_name":"Landmann","full_name":"Landmann, Marc","first_name":"Marc"},{"full_name":"Rauls, Eva","last_name":"Rauls","first_name":"Eva"},{"last_name":"Argiolas","full_name":"Argiolas, Nicola","first_name":"Nicola"},{"first_name":"Simone","full_name":"Sanna, Simone","last_name":"Sanna"},{"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"}],"doi":"10.1155/2017/3981317","type":"journal_article","status":"public","_id":"10023","project":[{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"},{"name":"TRR 142","_id":"53"},{"_id":"55","name":"TRR 142 - Project Area B"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"15"},{"_id":"35"},{"_id":"27"}],"user_id":"16199","isi":"1","article_number":"3981317","article_type":"original","file_date_updated":"2020-08-30T14:37:31Z","quality_controlled":"1","year":"2017","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","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":[{"relation":"main_file","date_updated":"2020-08-30T14:37:31Z","date_created":"2020-08-28T09:27:19Z","title":"Consistent atomic geometries and electronic structure of five phases of potassium niobate from density-functional theory","description":"Creative Commons Attribution 4.0 International Public License (CC BY 4.0)","access_level":"open_access","file_id":"18538","content_type":"application/pdf","creator":"schindlm","file_size":985948,"file_name":"3981317.pdf"}],"external_id":{"isi":["000394873300001"]},"ddc":["530"],"language":[{"iso":"eng"}]},{"publisher":"American Physical Society","date_created":"2019-05-29T07:42:33Z","title":"Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory","quality_controlled":"1","issue":"3","year":"2017","external_id":{"isi":["000416562300001"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"Physical Review Materials","abstract":[{"lang":"eng","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."}],"file":[{"content_type":"application/pdf","file_name":"PhysRevMaterials.1.034401.pdf","file_size":708075,"creator":"schindlm","relation":"main_file","file_id":"18467","access_level":"open_access","description":"© 2017 American Physical Society","title":"Optical properties of titanium-doped lithium niobate from time-dependent density-functional theory","date_created":"2020-08-27T19:39:54Z","date_updated":"2020-08-30T14:36:11Z"}],"oa":"1","date_updated":"2025-12-05T10:07:07Z","author":[{"last_name":"Friedrich","full_name":"Friedrich, Michael","first_name":"Michael"},{"first_name":"Wolf Gero","last_name":"Schmidt","orcid":"0000-0002-2717-5076","id":"468","full_name":"Schmidt, Wolf Gero"},{"first_name":"Arno","full_name":"Schindlmayr, Arno","id":"458","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr"},{"last_name":"Sanna","full_name":"Sanna, Simone","first_name":"Simone"}],"volume":1,"doi":"10.1103/PhysRevMaterials.1.034401","publication_status":"published","has_accepted_license":"1","publication_identifier":{"issn":["2475-9953"]},"related_material":{"record":[{"status":"public","id":"13410","relation":"other"}]},"citation":{"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>.","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>","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>","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} }","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)."},"intvolume":"         1","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"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"name":"TRR 142 - Subproject B3","_id":"68"}],"_id":"10021","user_id":"16199","department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"35"},{"_id":"27"}],"article_number":"034401","isi":"1","article_type":"original","file_date_updated":"2020-08-30T14:36:11Z","type":"journal_article","status":"public"},{"publisher":"American Physical Society","date_created":"2019-09-20T11:54:25Z","title":"Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory","quality_controlled":"1","issue":"5","year":"2017","external_id":{"isi":["000416586100003"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"Physical Review Materials","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."}],"file":[{"date_updated":"2020-08-30T14:38:50Z","creator":"schindlm","date_created":"2020-08-27T19:43:49Z","title":"Polaron optical absorption in congruent lithium niobate from time-dependent density-functional theory","description":"© 2017 American Physical Society","file_size":1417182,"access_level":"open_access","file_name":"PhysRevMaterials.1.054406.pdf","file_id":"18468","content_type":"application/pdf","relation":"main_file"}],"date_updated":"2025-12-05T10:14:23Z","oa":"1","volume":1,"author":[{"first_name":"Michael","full_name":"Friedrich, Michael","last_name":"Friedrich"},{"full_name":"Schmidt, Wolf Gero","id":"468","orcid":"0000-0002-2717-5076","last_name":"Schmidt","first_name":"Wolf Gero"},{"full_name":"Schindlmayr, Arno","id":"458","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","first_name":"Arno"},{"full_name":"Sanna, Simone","last_name":"Sanna","first_name":"Simone"}],"doi":"10.1103/PhysRevMaterials.1.054406","has_accepted_license":"1","publication_identifier":{"eissn":["2475-9953"]},"publication_status":"published","intvolume":"         1","citation":{"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>","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>.","short":"M. Friedrich, W.G. Schmidt, A. Schindlmayr, S. Sanna, Physical Review Materials 1 (2017).","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>.","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>"},"_id":"13416","project":[{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"_id":"53","name":"TRR 142"},{"_id":"55","name":"TRR 142 - Project Area B"},{"name":"TRR 142 - Subproject B3","_id":"68"},{"name":"TRR 142 - Subproject B4","_id":"69"}],"department":[{"_id":"296"},{"_id":"295"},{"_id":"230"},{"_id":"429"},{"_id":"35"},{"_id":"15"},{"_id":"27"}],"user_id":"16199","isi":"1","article_number":"054406","article_type":"original","file_date_updated":"2020-08-30T14:38:50Z","type":"journal_article","status":"public"},{"title":"Zn–VI quasiparticle gaps and optical spectra from many-body calculations","publisher":"IOP Publishing","date_created":"2019-02-04T13:46:58Z","year":"2017","quality_controlled":"1","issue":"21","ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"isi":["000400093100001"],"pmid":["28374685"]},"abstract":[{"lang":"eng","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."}],"file":[{"creator":"schindlm","date_created":"2020-08-28T14:01:15Z","date_updated":"2020-08-30T14:34:08Z","file_id":"18574","access_level":"closed","file_name":"Riefer_2017_J._Phys. _Condens._Matter_29_215702.pdf","title":"Zn–VI quasiparticle gaps and optical spectra from many-body calculations","file_size":2551657,"description":"© 2017 IOP Publishing Ltd","content_type":"application/pdf","relation":"main_file"}],"publication":"Journal of Physics: Condensed Matter","doi":"10.1088/1361-648x/aa6b2a","date_updated":"2025-12-16T11:07:33Z","author":[{"first_name":"Arthur","full_name":"Riefer, Arthur","last_name":"Riefer"},{"last_name":"Weber","full_name":"Weber, Nils","first_name":"Nils"},{"first_name":"Johannes","full_name":"Mund, Johannes","last_name":"Mund"},{"full_name":"Yakovlev, Dmitri R.","last_name":"Yakovlev","first_name":"Dmitri R."},{"full_name":"Bayer, Manfred","last_name":"Bayer","first_name":"Manfred"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","id":"458","full_name":"Schindlmayr, Arno"},{"orcid":"https://orcid.org/0000-0002-3787-3572","last_name":"Meier","id":"20798","full_name":"Meier, Cedrik","first_name":"Cedrik"},{"first_name":"Wolf Gero","id":"468","full_name":"Schmidt, Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt"}],"volume":29,"citation":{"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>.","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>.","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>","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).","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>.","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>"},"intvolume":"        29","publication_status":"published","pmid":"1","has_accepted_license":"1","publication_identifier":{"eissn":["1361-648X"],"issn":["0953-8984"]},"article_number":"215702","isi":"1","article_type":"original","file_date_updated":"2020-08-30T14:34:08Z","project":[{"name":"TRR 142","_id":"53"},{"_id":"55","name":"TRR 142 - Project Area B"},{"_id":"66","name":"TRR 142 - Subproject B1"},{"name":"TRR 142 - Subproject B4","_id":"69"},{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"_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"}],"status":"public","type":"journal_article"},{"date_updated":"2025-12-05T09:59:57Z","oa":"1","author":[{"full_name":"Riefer, Arthur","last_name":"Riefer","first_name":"Arthur"},{"last_name":"Friedrich","full_name":"Friedrich, Michael","first_name":"Michael"},{"first_name":"Simone","full_name":"Sanna, Simone","last_name":"Sanna"},{"first_name":"Uwe","full_name":"Gerstmann, Uwe","id":"171","orcid":"0000-0002-4476-223X","last_name":"Gerstmann"},{"full_name":"Schindlmayr, Arno","id":"458","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","first_name":"Arno"},{"id":"468","full_name":"Schmidt, Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt","first_name":"Wolf Gero"}],"volume":93,"doi":"10.1103/PhysRevB.93.075205","publication_status":"published","has_accepted_license":"1","publication_identifier":{"eissn":["2469-9969"],"issn":["2469-9950"]},"citation":{"short":"A. Riefer, M. Friedrich, S. Sanna, U. Gerstmann, A. Schindlmayr, W.G. Schmidt, Physical Review B 93 (2016).","bibtex":"@article{Riefer_Friedrich_Sanna_Gerstmann_Schindlmayr_Schmidt_2016, title={LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects}, volume={93}, DOI={<a href=\"https://doi.org/10.1103/PhysRevB.93.075205\">10.1103/PhysRevB.93.075205</a>}, number={7075205}, journal={Physical Review B}, publisher={American Physical Society}, author={Riefer, Arthur and Friedrich, Michael and Sanna, Simone and Gerstmann, Uwe and Schindlmayr, Arno and Schmidt, Wolf Gero}, year={2016} }","mla":"Riefer, Arthur, et al. “LiNbO3 Electronic Structure: Many-Body Interactions, Spin-Orbit Coupling, and Thermal Effects.” <i>Physical Review B</i>, vol. 93, no. 7, 075205, American Physical Society, 2016, doi:<a href=\"https://doi.org/10.1103/PhysRevB.93.075205\">10.1103/PhysRevB.93.075205</a>.","apa":"Riefer, A., Friedrich, M., Sanna, S., Gerstmann, U., Schindlmayr, A., &#38; Schmidt, W. G. (2016). LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects. <i>Physical Review B</i>, <i>93</i>(7), Article 075205. <a href=\"https://doi.org/10.1103/PhysRevB.93.075205\">https://doi.org/10.1103/PhysRevB.93.075205</a>","ama":"Riefer A, Friedrich M, Sanna S, Gerstmann U, Schindlmayr A, Schmidt WG. LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects. <i>Physical Review B</i>. 2016;93(7). doi:<a href=\"https://doi.org/10.1103/PhysRevB.93.075205\">10.1103/PhysRevB.93.075205</a>","chicago":"Riefer, Arthur, Michael Friedrich, Simone Sanna, Uwe Gerstmann, Arno Schindlmayr, and Wolf Gero Schmidt. “LiNbO3 Electronic Structure: Many-Body Interactions, Spin-Orbit Coupling, and Thermal Effects.” <i>Physical Review B</i> 93, no. 7 (2016). <a href=\"https://doi.org/10.1103/PhysRevB.93.075205\">https://doi.org/10.1103/PhysRevB.93.075205</a>.","ieee":"A. Riefer, M. Friedrich, S. Sanna, U. Gerstmann, A. Schindlmayr, and W. G. Schmidt, “LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects,” <i>Physical Review B</i>, vol. 93, no. 7, Art. no. 075205, 2016, doi: <a href=\"https://doi.org/10.1103/PhysRevB.93.075205\">10.1103/PhysRevB.93.075205</a>."},"intvolume":"        93","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"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"_id":"10024","user_id":"16199","department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"790"},{"_id":"15"},{"_id":"35"},{"_id":"27"}],"article_number":"075205","article_type":"original","isi":"1","file_date_updated":"2020-08-30T14:39:23Z","type":"journal_article","status":"public","publisher":"American Physical Society","date_created":"2019-05-29T07:50:59Z","title":"LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects","quality_controlled":"1","issue":"7","year":"2016","external_id":{"isi":["000370794800004"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"Physical Review B","abstract":[{"text":"The influence of electronic many-body interactions, spin-orbit coupling, and thermal lattice vibrations on the electronic structure of lithium niobate is calculated from first principles. Self-energy calculations in the GW approximation show that the inclusion of self-consistency in the Green function G and the screened Coulomb potential W opens the band gap far stronger than found in previous G0W0 calculations but slightly overestimates its actual value due to the neglect of excitonic effects in W. A realistic frozen-lattice band gap of about 5.9 eV is obtained by combining hybrid density functional theory with the QSGW0 scheme. The renormalization of the band gap due to electron-phonon coupling, derived here using molecular dynamics as well as density functional perturbation theory, reduces this value by about 0.5 eV at room temperature. Spin-orbit coupling does not noticeably modify the fundamental gap but gives rise to a Rashba-like spin texture in the conduction band.","lang":"eng"}],"file":[{"relation":"main_file","date_created":"2020-08-27T20:36:43Z","date_updated":"2020-08-30T14:39:23Z","access_level":"open_access","file_id":"18469","title":"LiNbO3 electronic structure: Many-body interactions, spin-orbit coupling, and thermal effects","description":"© 2016 American Physical Society","content_type":"application/pdf","creator":"schindlm","file_name":"PhysRevB.93.075205.pdf","file_size":1314637}]},{"publication_identifier":{"eissn":["1521-3951"],"issn":["0370-1972"]},"has_accepted_license":"1","publication_status":"published","intvolume":"       253","page":"683-689","citation":{"chicago":"Friedrich, Michael, Arno Schindlmayr, Wolf Gero Schmidt, and Simone Sanna. “LiTaO3 Phonon Dispersion and Ferroelectric Transition Calculated from First Principles.” <i>Physica Status Solidi B</i> 253, no. 4 (2016): 683–89. <a href=\"https://doi.org/10.1002/pssb.201552576\">https://doi.org/10.1002/pssb.201552576</a>.","ieee":"M. Friedrich, A. Schindlmayr, W. G. Schmidt, and S. Sanna, “LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles,” <i>Physica Status Solidi B</i>, vol. 253, no. 4, pp. 683–689, 2016, doi: <a href=\"https://doi.org/10.1002/pssb.201552576\">10.1002/pssb.201552576</a>.","ama":"Friedrich M, Schindlmayr A, Schmidt WG, Sanna S. LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles. <i>Physica Status Solidi B</i>. 2016;253(4):683-689. doi:<a href=\"https://doi.org/10.1002/pssb.201552576\">10.1002/pssb.201552576</a>","apa":"Friedrich, M., Schindlmayr, A., Schmidt, W. G., &#38; Sanna, S. (2016). LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles. <i>Physica Status Solidi B</i>, <i>253</i>(4), 683–689. <a href=\"https://doi.org/10.1002/pssb.201552576\">https://doi.org/10.1002/pssb.201552576</a>","mla":"Friedrich, Michael, et al. “LiTaO3 Phonon Dispersion and Ferroelectric Transition Calculated from First Principles.” <i>Physica Status Solidi B</i>, vol. 253, no. 4, Wiley-VCH, 2016, pp. 683–89, doi:<a href=\"https://doi.org/10.1002/pssb.201552576\">10.1002/pssb.201552576</a>.","short":"M. Friedrich, A. Schindlmayr, W.G. Schmidt, S. Sanna, Physica Status Solidi B 253 (2016) 683–689.","bibtex":"@article{Friedrich_Schindlmayr_Schmidt_Sanna_2016, title={LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles}, volume={253}, DOI={<a href=\"https://doi.org/10.1002/pssb.201552576\">10.1002/pssb.201552576</a>}, number={4}, journal={Physica Status Solidi B}, publisher={Wiley-VCH}, author={Friedrich, Michael and Schindlmayr, Arno and Schmidt, Wolf Gero and Sanna, Simone}, year={2016}, pages={683–689} }"},"date_updated":"2025-12-05T09:58:55Z","volume":253,"author":[{"full_name":"Friedrich, Michael","last_name":"Friedrich","first_name":"Michael"},{"full_name":"Schindlmayr, Arno","id":"458","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","first_name":"Arno"},{"first_name":"Wolf Gero","orcid":"0000-0002-2717-5076","last_name":"Schmidt","id":"468","full_name":"Schmidt, Wolf Gero"},{"full_name":"Sanna, Simone","last_name":"Sanna","first_name":"Simone"}],"doi":"10.1002/pssb.201552576","type":"journal_article","status":"public","_id":"10025","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"},{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"}],"department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"15"},{"_id":"35"},{"_id":"27"}],"user_id":"16199","isi":"1","article_type":"original","file_date_updated":"2020-08-30T14:41:39Z","quality_controlled":"1","issue":"4","year":"2016","publisher":"Wiley-VCH","date_created":"2019-05-29T07:52:52Z","title":"LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles","publication":"Physica Status Solidi B","abstract":[{"lang":"eng","text":"The phonon dispersions of the ferro‐ and paraelectric phase of LiTaO3 are calculated within density‐functional perturbation theory. The longitudinal optical phonon modes are theoretically derived and compared with available experimental data. Our results confirm the recent phonon assignment proposed by Margueron et al. [J. Appl. Phys. 111, 104105 (2012)] on the basis of spectroscopical studies. A comparison with the phonon band structure of the related material LiNbO3 shows minor differences that can be traced to the atomic‐mass difference between Ta and Nb. The presence of phonons with imaginary frequencies for the paraelectric phase suggests that it does not correspond to a minimum energy structure, and is compatible with an order‐disorder type phase transition."}],"file":[{"date_updated":"2020-08-30T14:41:39Z","date_created":"2020-08-28T14:22:11Z","creator":"schindlm","description":"© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim","file_size":402594,"title":"LiTaO3 phonon dispersion and ferroelectric transition calculated from first principles","file_id":"18577","access_level":"closed","file_name":"pssb.201552576.pdf","content_type":"application/pdf","relation":"main_file"}],"external_id":{"isi":["000374142500015"]},"ddc":["530"],"language":[{"iso":"eng"}]},{"ddc":["530"],"language":[{"iso":"eng"}],"external_id":{"pmid":["26337951"],"isi":["000362549700004"]},"abstract":[{"text":"The vibrational properties of stoichiometric LiNbO3 are analyzed within density-functional perturbation theory in order to obtain the complete phonon dispersion of the material. The phonon density of states of the ferroelectric (paraelectric) phase shows two (one) distinct band gaps separating the high-frequency (~800 cm−1) optical branches from the continuum of acoustic and lower optical phonon states. This result leads to specific heat capacites in close agreement with experimental measurements in the range 0–350 K and a Debye temperature of 574 K. The calculated zero-point renormalization of the electronic Kohn–Sham eigenvalues reveals a strong dependence on the phonon wave vectors, especially near Γ. Integrated over all phonon modes, our results indicate a vibrational correction of the electronic band gap of 0.41 eV at 0 K, which is in excellent agreement with the extrapolated temperature-dependent measurements.","lang":"eng"}],"file":[{"creator":"schindlm","file_name":"Friedrich_2015_J._Phys. _Condens._Matter_27_385402.pdf","file_size":1793430,"content_type":"application/pdf","date_created":"2020-08-28T14:24:23Z","date_updated":"2020-08-30T14:46:56Z","access_level":"closed","file_id":"18578","title":"Phonon dispersion and zero-point renormalization of LiNbO3 from density-functional perturbation theory","description":"© 2015 IOP Publishing Ltd","relation":"main_file"}],"publication":"Journal of Physics: Condensed Matter","title":"Phonon dispersion and zero-point renormalization of LiNbO3 from density-functional perturbation theory","publisher":"IOP Publishing","date_created":"2019-05-29T08:41:18Z","year":"2015","quality_controlled":"1","issue":"38","article_number":"385402","isi":"1","article_type":"original","file_date_updated":"2020-08-30T14:46:56Z","project":[{"name":"Computing Resources Provided by the Paderborn Center for Parallel Computing","_id":"52"},{"_id":"53","name":"TRR 142"},{"_id":"55","name":"TRR 142 - Project Area B"},{"_id":"69","name":"TRR 142 - Subproject B4"},{"_id":"52","name":"Computing Resources Provided by the Paderborn Center for Parallel Computing"}],"_id":"10030","user_id":"16199","department":[{"_id":"295"},{"_id":"296"},{"_id":"230"},{"_id":"429"},{"_id":"15"},{"_id":"35"},{"_id":"27"}],"status":"public","type":"journal_article","doi":"10.1088/0953-8984/27/38/385402","date_updated":"2025-12-05T10:00:42Z","author":[{"first_name":"Michael","full_name":"Friedrich, Michael","last_name":"Friedrich"},{"last_name":"Riefer","full_name":"Riefer, Arthur","first_name":"Arthur"},{"last_name":"Sanna","full_name":"Sanna, Simone","first_name":"Simone"},{"first_name":"Wolf Gero","full_name":"Schmidt, Wolf Gero","id":"468","orcid":"0000-0002-2717-5076","last_name":"Schmidt"},{"orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","id":"458","full_name":"Schindlmayr, Arno","first_name":"Arno"}],"volume":27,"citation":{"chicago":"Friedrich, Michael, Arthur Riefer, Simone Sanna, Wolf Gero Schmidt, and Arno Schindlmayr. “Phonon Dispersion and Zero-Point Renormalization of LiNbO3 from Density-Functional Perturbation Theory.” <i>Journal of Physics: Condensed Matter</i> 27, no. 38 (2015). <a href=\"https://doi.org/10.1088/0953-8984/27/38/385402\">https://doi.org/10.1088/0953-8984/27/38/385402</a>.","ieee":"M. Friedrich, A. Riefer, S. Sanna, W. G. Schmidt, and A. Schindlmayr, “Phonon dispersion and zero-point renormalization of LiNbO3 from density-functional perturbation theory,” <i>Journal of Physics: Condensed Matter</i>, vol. 27, no. 38, Art. no. 385402, 2015, doi: <a href=\"https://doi.org/10.1088/0953-8984/27/38/385402\">10.1088/0953-8984/27/38/385402</a>.","ama":"Friedrich M, Riefer A, Sanna S, Schmidt WG, Schindlmayr A. Phonon dispersion and zero-point renormalization of LiNbO3 from density-functional perturbation theory. <i>Journal of Physics: Condensed Matter</i>. 2015;27(38). doi:<a href=\"https://doi.org/10.1088/0953-8984/27/38/385402\">10.1088/0953-8984/27/38/385402</a>","mla":"Friedrich, Michael, et al. “Phonon Dispersion and Zero-Point Renormalization of LiNbO3 from Density-Functional Perturbation Theory.” <i>Journal of Physics: Condensed Matter</i>, vol. 27, no. 38, 385402, IOP Publishing, 2015, doi:<a href=\"https://doi.org/10.1088/0953-8984/27/38/385402\">10.1088/0953-8984/27/38/385402</a>.","short":"M. Friedrich, A. Riefer, S. Sanna, W.G. Schmidt, A. Schindlmayr, Journal of Physics: Condensed Matter 27 (2015).","bibtex":"@article{Friedrich_Riefer_Sanna_Schmidt_Schindlmayr_2015, title={Phonon dispersion and zero-point renormalization of LiNbO3 from density-functional perturbation theory}, volume={27}, DOI={<a href=\"https://doi.org/10.1088/0953-8984/27/38/385402\">10.1088/0953-8984/27/38/385402</a>}, number={38385402}, journal={Journal of Physics: Condensed Matter}, publisher={IOP Publishing}, author={Friedrich, Michael and Riefer, Arthur and Sanna, Simone and Schmidt, Wolf Gero and Schindlmayr, Arno}, year={2015} }","apa":"Friedrich, M., Riefer, A., Sanna, S., Schmidt, W. G., &#38; Schindlmayr, A. (2015). Phonon dispersion and zero-point renormalization of LiNbO3 from density-functional perturbation theory. <i>Journal of Physics: Condensed Matter</i>, <i>27</i>(38), Article 385402. <a href=\"https://doi.org/10.1088/0953-8984/27/38/385402\">https://doi.org/10.1088/0953-8984/27/38/385402</a>"},"intvolume":"        27","publication_status":"published","publication_identifier":{"eissn":["1361-648X"],"issn":["0953-8984"]},"pmid":"1","has_accepted_license":"1"},{"oa":"1","date_updated":"2025-12-16T11:08:01Z","volume":2015,"author":[{"full_name":"Bouhassoune, Mohammed","last_name":"Bouhassoune","first_name":"Mohammed"},{"first_name":"Arno","orcid":"0000-0002-4855-071X","last_name":"Schindlmayr","full_name":"Schindlmayr, Arno","id":"458"}],"doi":"10.1155/2015/453125","publication_identifier":{"eissn":["1687-8124"],"issn":["1687-8108"]},"has_accepted_license":"1","publication_status":"published","intvolume":"      2015","citation":{"ieee":"M. Bouhassoune and A. Schindlmayr, “Ab initio study of strain effects on the quasiparticle bands and effective masses in silicon,” <i>Advances in Condensed Matter Physics</i>, vol. 2015, Art. no. 453125, 2015, doi: <a href=\"https://doi.org/10.1155/2015/453125\">10.1155/2015/453125</a>.","chicago":"Bouhassoune, Mohammed, and Arno Schindlmayr. “Ab Initio Study of Strain Effects on the Quasiparticle Bands and Effective Masses in Silicon.” <i>Advances in Condensed Matter Physics</i> 2015 (2015). <a href=\"https://doi.org/10.1155/2015/453125\">https://doi.org/10.1155/2015/453125</a>.","ama":"Bouhassoune M, Schindlmayr A. Ab initio study of strain effects on the quasiparticle bands and effective masses in silicon. <i>Advances in Condensed Matter Physics</i>. 2015;2015. doi:<a href=\"https://doi.org/10.1155/2015/453125\">10.1155/2015/453125</a>","short":"M. Bouhassoune, A. Schindlmayr, Advances in Condensed Matter Physics 2015 (2015).","mla":"Bouhassoune, Mohammed, and Arno Schindlmayr. “Ab Initio Study of Strain Effects on the Quasiparticle Bands and Effective Masses in Silicon.” <i>Advances in Condensed Matter Physics</i>, vol. 2015, 453125, Hindawi, 2015, doi:<a href=\"https://doi.org/10.1155/2015/453125\">10.1155/2015/453125</a>.","bibtex":"@article{Bouhassoune_Schindlmayr_2015, title={Ab initio study of strain effects on the quasiparticle bands and effective masses in silicon}, volume={2015}, DOI={<a href=\"https://doi.org/10.1155/2015/453125\">10.1155/2015/453125</a>}, number={453125}, journal={Advances in Condensed Matter Physics}, publisher={Hindawi}, author={Bouhassoune, Mohammed and Schindlmayr, Arno}, year={2015} }","apa":"Bouhassoune, M., &#38; Schindlmayr, A. (2015). Ab initio study of strain effects on the quasiparticle bands and effective masses in silicon. <i>Advances in Condensed Matter Physics</i>, <i>2015</i>, Article 453125. <a href=\"https://doi.org/10.1155/2015/453125\">https://doi.org/10.1155/2015/453125</a>"},"_id":"18470","department":[{"_id":"296"},{"_id":"35"},{"_id":"15"},{"_id":"170"},{"_id":"230"}],"user_id":"16199","article_type":"original","isi":"1","article_number":"453125","file_date_updated":"2020-08-30T14:45:29Z","type":"journal_article","status":"public","publisher":"Hindawi","date_created":"2020-08-27T20:45:37Z","title":"Ab initio study of strain effects on the quasiparticle bands and effective masses in silicon","quality_controlled":"1","year":"2015","external_id":{"isi":["000350656500001"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"Advances in Condensed Matter Physics","abstract":[{"lang":"eng","text":"Using ab initio computational methods, we study the structural and electronic properties of strained silicon, which has emerged as a promising technology to improve the performance of silicon-based metal-oxide-semiconductor field-effect transistors. In particular, higher electron mobilities are observed in n-doped samples with monoclinic strain along the [110] direction, and experimental evidence relates this to changes in the effective mass as well as the scattering rates. To assess the relative importance of these two factors, we combine density-functional theory in the local-density approximation with the GW approximation for the electronic self-energy and investigate the effect of uniaxial and biaxial strains along the [110] direction on the structural and electronic properties of Si. Longitudinal and transverse components of the electron effective mass as a function of the strain are derived from fits to the quasiparticle band structure and a diagonalization of the full effective-mass tensor. The changes in the effective masses and the energy splitting of the conduction-band valleys for uniaxial and biaxial strains as well as their impact on the electron mobility are analyzed. The self-energy corrections within GW lead to band gaps in excellent agreement with experimental measurements and slightly larger effective masses than in the local-density approximation."}],"file":[{"date_updated":"2020-08-30T14:45:29Z","date_created":"2020-08-28T09:42:44Z","description":"Creative Commons Attribution 3.0 Unported Public License (CC BY 3.0)","title":"Ab initio study of strain effects on the quasiparticle bands and effective masses in silicon","file_id":"18540","access_level":"open_access","relation":"main_file","creator":"schindlm","file_size":560248,"file_name":"453125.pdf","content_type":"application/pdf"}]},{"date_updated":"2025-12-16T08:06:12Z","author":[{"last_name":"Friedrich","full_name":"Friedrich, Christoph","first_name":"Christoph"},{"first_name":"Ersoy","last_name":"Şaşıoğlu","full_name":"Şaşıoğlu, Ersoy"},{"first_name":"Mathias","full_name":"Müller, Mathias","last_name":"Müller"},{"first_name":"Arno","last_name":"Schindlmayr","orcid":"0000-0002-4855-071X","id":"458","full_name":"Schindlmayr, Arno"},{"full_name":"Blügel, Stefan","last_name":"Blügel","first_name":"Stefan"}],"volume":347,"doi":"10.1007/128_2013_518","publication_status":"published","publication_identifier":{"issn":["0340-1022"],"eissn":["1436-5049"],"isbn":["978-3-642-55067-6"],"eisbn":["978-3-642-55068-3"]},"pmid":"1","has_accepted_license":"1","place":"Berlin, Heidelberg","citation":{"ieee":"C. Friedrich, E. Şaşıoğlu, M. Müller, A. Schindlmayr, and S. Blügel, “Spin excitations in solids from many-body perturbation theory,” in <i>First Principles Approaches to Spectroscopic Properties of Complex Materials</i>, vol. 347, C. Di Valentin, S. Botti, and M. Cococcioni, Eds. Berlin, Heidelberg: Springer, 2014, pp. 259–301.","chicago":"Friedrich, Christoph, Ersoy Şaşıoğlu, Mathias Müller, Arno Schindlmayr, and Stefan Blügel. “Spin Excitations in Solids from Many-Body Perturbation Theory.” In <i>First Principles Approaches to Spectroscopic Properties of Complex Materials</i>, edited by Cristiana Di Valentin, Silvana Botti, and Matteo Cococcioni, 347:259–301.  Topics in Current Chemistry. Berlin, Heidelberg: Springer, 2014. <a href=\"https://doi.org/10.1007/128_2013_518\">https://doi.org/10.1007/128_2013_518</a>.","ama":"Friedrich C, Şaşıoğlu E, Müller M, Schindlmayr A, Blügel S. Spin excitations in solids from many-body perturbation theory. In: Di Valentin C, Botti S, Cococcioni M, eds. <i>First Principles Approaches to Spectroscopic Properties of Complex Materials</i>. Vol 347.  Topics in Current Chemistry. Springer; 2014:259-301. doi:<a href=\"https://doi.org/10.1007/128_2013_518\">10.1007/128_2013_518</a>","short":"C. Friedrich, E. Şaşıoğlu, M. Müller, A. Schindlmayr, S. Blügel, in: C. Di Valentin, S. Botti, M. Cococcioni (Eds.), First Principles Approaches to Spectroscopic Properties of Complex Materials, Springer, Berlin, Heidelberg, 2014, pp. 259–301.","mla":"Friedrich, Christoph, et al. “Spin Excitations in Solids from Many-Body Perturbation Theory.” <i>First Principles Approaches to Spectroscopic Properties of Complex Materials</i>, edited by Cristiana Di Valentin et al., vol. 347, Springer, 2014, pp. 259–301, doi:<a href=\"https://doi.org/10.1007/128_2013_518\">10.1007/128_2013_518</a>.","bibtex":"@inbook{Friedrich_Şaşıoğlu_Müller_Schindlmayr_Blügel_2014, place={Berlin, Heidelberg}, series={ Topics in Current Chemistry}, title={Spin excitations in solids from many-body perturbation theory}, volume={347}, DOI={<a href=\"https://doi.org/10.1007/128_2013_518\">10.1007/128_2013_518</a>}, booktitle={First Principles Approaches to Spectroscopic Properties of Complex Materials}, publisher={Springer}, author={Friedrich, Christoph and Şaşıoğlu, Ersoy and Müller, Mathias and Schindlmayr, Arno and Blügel, Stefan}, editor={Di Valentin, Cristiana and Botti, Silvana and Cococcioni, Matteo}, year={2014}, pages={259–301}, collection={ Topics in Current Chemistry} }","apa":"Friedrich, C., Şaşıoğlu, E., Müller, M., Schindlmayr, A., &#38; Blügel, S. (2014). Spin excitations in solids from many-body perturbation theory. In C. Di Valentin, S. Botti, &#38; M. Cococcioni (Eds.), <i>First Principles Approaches to Spectroscopic Properties of Complex Materials</i> (Vol. 347, pp. 259–301). Springer. <a href=\"https://doi.org/10.1007/128_2013_518\">https://doi.org/10.1007/128_2013_518</a>"},"intvolume":"       347","page":"259-301","_id":"18471","series_title":" Topics in Current Chemistry","user_id":"16199","department":[{"_id":"296"},{"_id":"35"},{"_id":"15"},{"_id":"230"}],"isi":"1","file_date_updated":"2020-08-30T14:48:45Z","type":"book_chapter","editor":[{"full_name":"Di Valentin, Cristiana","last_name":"Di Valentin","first_name":"Cristiana"},{"first_name":"Silvana","last_name":"Botti","full_name":"Botti, Silvana"},{"full_name":"Cococcioni, Matteo","last_name":"Cococcioni","first_name":"Matteo"}],"status":"public","publisher":"Springer","date_created":"2020-08-27T21:00:45Z","title":"Spin excitations in solids from many-body perturbation theory","quality_controlled":"1","year":"2014","external_id":{"isi":["000356811000008"],"pmid":["24577607"]},"ddc":["530"],"language":[{"iso":"eng"}],"publication":"First Principles Approaches to Spectroscopic Properties of Complex Materials","abstract":[{"text":"Collective spin excitations form a fundamental class of excitations in magnetic materials. As their energy reaches down to only a few meV, they are present at all temperatures and substantially influence the properties of magnetic systems. To study the spin excitations in solids from first principles, we have developed a computational scheme based on many-body perturbation theory within the full-potential linearized augmented plane-wave (FLAPW) method. The main quantity of interest is the dynamical transverse spin susceptibility or magnetic response function, from which magnetic excitations, including single-particle spin-flip Stoner excitations and collective spin-wave modes as well as their lifetimes, can be obtained. In order to describe spin waves we include appropriate vertex corrections in the form of a multiple-scattering T matrix, which describes the coupling of electrons and holes with different spins. The electron–hole interaction incorporates the screening of the many-body system within the random-phase approximation. To reduce the numerical cost in evaluating the four-point T matrix, we exploit a transformation to maximally localized Wannier functions that takes advantage of the short spatial range of electronic correlation in the partially filled d or f orbitals of magnetic materials. The theory and the implementation are discussed in detail. In particular, we show how the magnetic response function can be evaluated for arbitrary k points. This enables the calculation of smooth dispersion curves, allowing one to study fine details in the k dependence of the spin-wave spectra. We also demonstrate how spatial and time-reversal symmetry can be exploited to accelerate substantially the computation of the four-point quantities. As an illustration, we present spin-wave spectra and dispersions for the elementary ferromagnet bcc Fe, B2-type tetragonal FeCo, and CrO2 calculated with our scheme. The results are in good agreement with available experimental data.","lang":"eng"}],"file":[{"relation":"main_file","content_type":"application/pdf","file_id":"18584","access_level":"closed","file_name":"Friedrich2014_Chapter_SpinExcitationsInSolidsFromMan.pdf","title":"Spin excitations in solids from many-body perturbation theory","description":"© 2014 Springer-Verlag, Berlin, Heidelberg","file_size":1061365,"creator":"schindlm","date_created":"2020-08-28T15:19:57Z","date_updated":"2020-08-30T14:48:45Z"}]}]