---
_id: '44088'
abstract:
- lang: eng
text: 'Hole polarons and defect-bound exciton polarons in lithium niobate are investigated
by means of density-functional theory, where the localization of the holes is
achieved by applying the +U approach to the oxygen 2p orbitals. We find three
principal configurations of hole polarons: (i) self-trapped holes localized at
displaced regular oxygen atoms and (ii) two other configurations bound to a lithium
vacancy either at a threefold coordinated oxygen atom above or at a two-fold coordinated
oxygen atom below the defect. The latter is the most stable and is in excellent
quantitative agreement with measured g factors from electron paramagnetic resonance.
Due to the absence of mid-gap states, none of these hole polarons can explain
the broad optical absorption centered between 2.5 and 2.8 eV that is observed
in transient absorption spectroscopy, but such states appear if a free electron
polaron is trapped at the same lithium vacancy as the bound hole polaron, resulting
in an exciton polaron. The dielectric function calculated by solving the Bethe–Salpeter
equation indeed yields an optical peak at 2.6 eV in agreement with the two-photon
experiments. The coexistence of hole and exciton polarons, which are simultaneously
created in optical excitations, thus satisfactorily explains the reported experimental
data.'
article_number: '1586'
article_type: original
author:
- first_name: Falko
full_name: Schmidt, Falko
id: '35251'
last_name: Schmidt
orcid: 0000-0002-5071-5528
- first_name: Agnieszka L.
full_name: Kozub, Agnieszka L.
id: '77566'
last_name: Kozub
orcid: 0000-0001-6584-0201
- first_name: Uwe
full_name: Gerstmann, Uwe
id: '171'
last_name: Gerstmann
orcid: 0000-0002-4476-223X
- first_name: Wolf Gero
full_name: Schmidt, Wolf Gero
id: '468'
last_name: Schmidt
orcid: 0000-0002-2717-5076
- first_name: Arno
full_name: Schindlmayr, Arno
id: '458'
last_name: Schindlmayr
orcid: 0000-0002-4855-071X
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. Crystals.
2022;12(11). doi:10.3390/cryst12111586
apa: Schmidt, F., Kozub, A. L., Gerstmann, U., Schmidt, W. G., & Schindlmayr,
A. (2022). A density-functional theory study of hole and defect-bound exciton
polarons in lithium niobate. Crystals, 12(11), Article 1586. https://doi.org/10.3390/cryst12111586
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={10.3390/cryst12111586},
number={111586}, journal={Crystals}, publisher={MDPI AG}, author={Schmidt, Falko
and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr,
Arno}, year={2022} }'
chicago: Schmidt, Falko, Agnieszka L. Kozub, Uwe Gerstmann, Wolf Gero Schmidt, and
Arno Schindlmayr. “A Density-Functional Theory Study of Hole and Defect-Bound
Exciton Polarons in Lithium Niobate.” Crystals 12, no. 11 (2022). https://doi.org/10.3390/cryst12111586.
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,” Crystals, vol. 12, no. 11, Art. no. 1586, 2022, doi:
10.3390/cryst12111586.'
mla: Schmidt, Falko, et al. “A Density-Functional Theory Study of Hole and Defect-Bound
Exciton Polarons in Lithium Niobate.” Crystals, vol. 12, no. 11, 1586,
MDPI AG, 2022, doi:10.3390/cryst12111586.
short: F. Schmidt, A.L. Kozub, U. Gerstmann, W.G. Schmidt, A. Schindlmayr, Crystals
12 (2022).
date_created: 2023-04-20T13:52:44Z
date_updated: 2025-09-18T13:28:05Z
ddc:
- '530'
department:
- _id: '15'
- _id: '296'
- _id: '170'
- _id: '295'
- _id: '35'
- _id: '230'
- _id: '429'
- _id: '27'
doi: 10.3390/cryst12111586
external_id:
isi:
- '000895837200001'
file:
- access_level: open_access
content_type: application/pdf
creator: schindlm
date_created: 2023-06-11T23:59:27Z
date_updated: 2023-06-12T00:22:51Z
description: Creative Commons Attribution 4.0 International Public License (CC BY
4.0)
file_id: '45570'
file_name: crystals-12-01586-v2.pdf
file_size: 1762554
relation: main_file
title: A density-functional theory study of hole and defect-bound exciton polarons
in lithium niobate
file_date_updated: 2023-06-12T00:22:51Z
has_accepted_license: '1'
intvolume: ' 12'
isi: '1'
issue: '11'
language:
- iso: eng
oa: '1'
project:
- _id: '53'
name: 'TRR 142: TRR 142'
- _id: '54'
name: 'TRR 142 - A: TRR 142 - Project Area A'
- _id: '55'
name: 'TRR 142 - B: TRR 142 - Project Area B'
- _id: '69'
name: 'TRR 142 - B04: TRR 142 - Subproject B04'
- _id: '168'
name: 'TRR 142 - B07: TRR 142 - Subproject B07'
- _id: '166'
name: 'TRR 142 - A11: TRR 142 - Subproject A11'
- _id: '52'
name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication: Crystals
publication_identifier:
eissn:
- 2073-4352
publication_status: published
publisher: MDPI AG
quality_controlled: '1'
status: public
title: A density-functional theory study of hole and defect-bound exciton polarons
in lithium niobate
type: journal_article
user_id: '16199'
volume: 12
year: '2022'
...
---
_id: '30288'
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.
author:
- first_name: Falko
full_name: Schmidt, Falko
id: '35251'
last_name: Schmidt
orcid: 0000-0002-5071-5528
- first_name: Agnieszka L.
full_name: Kozub, Agnieszka L.
id: '77566'
last_name: Kozub
orcid: https://orcid.org/0000-0001-6584-0201
- first_name: Uwe
full_name: Gerstmann, Uwe
id: '171'
last_name: Gerstmann
orcid: 0000-0002-4476-223X
- first_name: Wolf Gero
full_name: Schmidt, Wolf Gero
id: '468'
last_name: Schmidt
orcid: 0000-0002-2717-5076
- first_name: Arno
full_name: Schindlmayr, Arno
id: '458'
last_name: Schindlmayr
orcid: 0000-0002-4855-071X
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. New Trends in Lithium Niobate: From Bulk to Nanocrystals.
MDPI; 2022:231-248. doi:10.3390/books978-3-0365-3339-1'
apa: 'Schmidt, F., Kozub, A. L., Gerstmann, U., Schmidt, W. G., & Schindlmayr,
A. (2022). Electron polarons in lithium niobate: Charge localization, lattice
deformation, and optical response. In G. Corradi & L. Kovács (Eds.), New
Trends in Lithium Niobate: From Bulk to Nanocrystals (pp. 231–248). MDPI.
https://doi.org/10.3390/books978-3-0365-3339-1'
bibtex: '@inbook{Schmidt_Kozub_Gerstmann_Schmidt_Schindlmayr_2022, place={Basel},
title={Electron polarons in lithium niobate: Charge localization, lattice deformation,
and optical response}, DOI={10.3390/books978-3-0365-3339-1},
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} }'
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 New Trends in Lithium Niobate:
From Bulk to Nanocrystals, edited by Gábor Corradi and László Kovács, 231–48.
Basel: MDPI, 2022. https://doi.org/10.3390/books978-3-0365-3339-1.'
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 New Trends in Lithium Niobate: From Bulk to Nanocrystals,
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.” New Trends in Lithium Niobate:
From Bulk to Nanocrystals, edited by Gábor Corradi and László Kovács, MDPI,
2022, pp. 231–48, doi:10.3390/books978-3-0365-3339-1.'
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.'
date_created: 2022-03-13T15:28:47Z
date_updated: 2025-12-05T14:00:04Z
ddc:
- '530'
department:
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '295'
- _id: '15'
- _id: '170'
- _id: '35'
- _id: '790'
doi: 10.3390/books978-3-0365-3339-1
editor:
- first_name: Gábor
full_name: Corradi, Gábor
last_name: Corradi
- first_name: László
full_name: Kovács, László
last_name: Kovács
language:
- iso: eng
page: 231-248
place: Basel
project:
- _id: '53'
name: 'TRR 142: TRR 142'
- _id: '55'
name: 'TRR 142 - B: TRR 142 - Project Area B'
- _id: '69'
name: 'TRR 142 - B4: TRR 142 - Subproject B4'
- _id: '54'
name: 'TRR 142 - A: TRR 142 - Project Area A'
- _id: '166'
name: 'TRR 142 - A11: TRR 142 - Subproject A11'
- _id: '168'
name: 'TRR 142 - B07: TRR 142 - Subproject B07'
- _id: '52'
name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
- _id: '53'
name: 'TRR 142: Maßgeschneiderte nichtlineare Photonik: Von grundlegenden Konzepten
zu funktionellen Strukturen'
publication: 'New Trends in Lithium Niobate: From Bulk to Nanocrystals'
publication_identifier:
eisbn:
- 978-3-0365-3339-1
isbn:
- 978-3-0365-3340-7
publication_status: published
publisher: MDPI
quality_controlled: '1'
status: public
title: 'Electron polarons in lithium niobate: Charge localization, lattice deformation,
and optical response'
type: book_chapter
user_id: '16199'
year: '2022'
...
---
_id: '21946'
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.
article_type: original
author:
- first_name: Falko
full_name: Schmidt, Falko
id: '35251'
last_name: Schmidt
orcid: 0000-0002-5071-5528
- first_name: Agnieszka L.
full_name: Kozub, Agnieszka L.
id: '77566'
last_name: Kozub
orcid: https://orcid.org/0000-0001-6584-0201
- first_name: Uwe
full_name: Gerstmann, Uwe
id: '171'
last_name: Gerstmann
orcid: 0000-0002-4476-223X
- first_name: Wolf Gero
full_name: Schmidt, Wolf Gero
id: '468'
last_name: Schmidt
orcid: 0000-0002-2717-5076
- first_name: Arno
full_name: Schindlmayr, Arno
id: '458'
last_name: Schindlmayr
orcid: 0000-0002-4855-071X
citation:
ama: 'Schmidt F, Kozub AL, Gerstmann U, Schmidt WG, Schindlmayr A. Electron polarons
in lithium niobate: Charge localization, lattice deformation, and optical response.
Crystals. 2021;11:542. doi:10.3390/cryst11050542'
apa: 'Schmidt, F., Kozub, A. L., Gerstmann, U., Schmidt, W. G., & Schindlmayr,
A. (2021). Electron polarons in lithium niobate: Charge localization, lattice
deformation, and optical response. Crystals, 11, 542. https://doi.org/10.3390/cryst11050542'
bibtex: '@article{Schmidt_Kozub_Gerstmann_Schmidt_Schindlmayr_2021, title={Electron
polarons in lithium niobate: Charge localization, lattice deformation, and optical
response}, volume={11}, DOI={10.3390/cryst11050542},
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} }'
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.” Crystals 11 (2021): 542. https://doi.org/10.3390/cryst11050542.'
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,” Crystals, vol. 11, p. 542, 2021, doi: 10.3390/cryst11050542.'
mla: 'Schmidt, Falko, et al. “Electron Polarons in Lithium Niobate: Charge Localization,
Lattice Deformation, and Optical Response.” Crystals, vol. 11, MDPI, 2021,
p. 542, doi:10.3390/cryst11050542.'
short: F. Schmidt, A.L. Kozub, U. Gerstmann, W.G. Schmidt, A. Schindlmayr, Crystals
11 (2021) 542.
date_created: 2021-05-03T09:36:13Z
date_updated: 2023-04-21T11:20:15Z
ddc:
- '530'
department:
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '295'
- _id: '15'
- _id: '170'
- _id: '35'
- _id: '790'
doi: 10.3390/cryst11050542
external_id:
isi:
- '000653822700001'
file:
- access_level: open_access
content_type: application/pdf
creator: schindlm
date_created: 2021-05-13T16:47:11Z
date_updated: 2021-05-13T16:51:41Z
description: Creative Commons Attribution 4.0 International Public License (CC BY
4.0)
file_id: '22163'
file_name: crystals-11-00542.pdf
file_size: 3042827
relation: main_file
title: 'Electron polarons in lithium niobate: Charge localization, lattice deformation,
and optical response'
file_date_updated: 2021-05-13T16:51:41Z
funded_apc: '1'
has_accepted_license: '1'
intvolume: ' 11'
isi: '1'
language:
- iso: eng
oa: '1'
page: '542'
project:
- _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: '52'
name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication: Crystals
publication_identifier:
eissn:
- 2073-4352
publication_status: published
publisher: MDPI
quality_controlled: '1'
status: public
title: 'Electron polarons in lithium niobate: Charge localization, lattice deformation,
and optical response'
type: journal_article
user_id: '171'
volume: 11
year: '2021'
...
---
_id: '22960'
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.
article_number: '169'
article_type: original
author:
- first_name: Nithin
full_name: Bidaraguppe Ramesh, Nithin
id: '70064'
last_name: Bidaraguppe Ramesh
- first_name: Falko
full_name: Schmidt, Falko
id: '35251'
last_name: Schmidt
orcid: 0000-0002-5071-5528
- first_name: Arno
full_name: Schindlmayr, Arno
id: '458'
last_name: Schindlmayr
orcid: 0000-0002-4855-071X
citation:
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. The European Physical Journal B. 2021;94(8). doi:10.1140/epjb/s10051-021-00179-8
apa: Bidaraguppe Ramesh, N., Schmidt, F., & Schindlmayr, A. (2021). Lattice
parameters and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3
from density-functional theory. The European Physical Journal B, 94(8),
Article 169. https://doi.org/10.1140/epjb/s10051-021-00179-8
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={10.1140/epjb/s10051-021-00179-8},
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} }'
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.” The European Physical Journal B 94, no.
8 (2021). https://doi.org/10.1140/epjb/s10051-021-00179-8.
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,” The European Physical Journal B, vol.
94, no. 8, Art. no. 169, 2021, doi: 10.1140/epjb/s10051-021-00179-8.'
mla: Bidaraguppe Ramesh, Nithin, et al. “Lattice Parameters and Electronic Band
Gap of Orthorhombic Potassium Sodium Niobate K0.5Na0.5NbO3 from Density-Functional
Theory.” The European Physical Journal B, vol. 94, no. 8, 169, EDP Sciences,
Società Italiana di Fisica and Springer, 2021, doi:10.1140/epjb/s10051-021-00179-8.
short: N. Bidaraguppe Ramesh, F. Schmidt, A. Schindlmayr, The European Physical
Journal B 94 (2021).
date_created: 2021-08-08T21:21:42Z
date_updated: 2023-04-20T14:56:25Z
ddc:
- '530'
department:
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '15'
- _id: '170'
- _id: '35'
doi: 10.1140/epjb/s10051-021-00179-8
external_id:
isi:
- '000687163200002'
file:
- access_level: open_access
content_type: application/pdf
creator: schindlm
date_created: 2021-09-02T08:05:06Z
date_updated: 2021-09-02T08:05:06Z
description: Creative Commons Attribution 4.0 International Public License (CC BY
4.0)
file_id: '23679'
file_name: BidaraguppeRamesh2021_Article_LatticeParametersAndElectronic.pdf
file_size: 850389
relation: main_file
title: Lattice parameters and electronic bandgap of orthorhombic potassium sodium
niobate K0.5Na0.5NbO3 from density-functional theory
file_date_updated: 2021-09-02T08:05:06Z
has_accepted_license: '1'
intvolume: ' 94'
isi: '1'
issue: '8'
language:
- iso: eng
oa: '1'
project:
- _id: '53'
name: TRR 142
- _id: '55'
name: TRR 142 - Project Area B
- _id: '69'
name: TRR 142 - Subproject B4
publication: The European Physical Journal B
publication_identifier:
eissn:
- 1434-6036
issn:
- 1434-6028
publication_status: published
publisher: EDP Sciences, Società Italiana di Fisica and Springer
quality_controlled: '1'
status: public
title: Lattice parameters and electronic band gap of orthorhombic potassium sodium
niobate K0.5Na0.5NbO3 from density-functional theory
type: journal_article
user_id: '16199'
volume: 94
year: '2021'
...
---
_id: '19190'
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."
article_number: '043002'
article_type: original
author:
- first_name: Falko
full_name: Schmidt, Falko
id: '35251'
last_name: Schmidt
orcid: 0000-0002-5071-5528
- first_name: Agnieszka L.
full_name: Kozub, Agnieszka L.
id: '77566'
last_name: Kozub
orcid: https://orcid.org/0000-0001-6584-0201
- first_name: Timur
full_name: Biktagirov, Timur
id: '65612'
last_name: Biktagirov
- first_name: Christof
full_name: Eigner, Christof
id: '13244'
last_name: Eigner
orcid: https://orcid.org/0000-0002-5693-3083
- first_name: Christine
full_name: Silberhorn, Christine
id: '26263'
last_name: Silberhorn
- first_name: Arno
full_name: Schindlmayr, Arno
id: '458'
last_name: Schindlmayr
orcid: 0000-0002-4855-071X
- first_name: Wolf Gero
full_name: Schmidt, Wolf Gero
id: '468'
last_name: Schmidt
orcid: 0000-0002-2717-5076
- first_name: Uwe
full_name: Gerstmann, Uwe
id: '171'
last_name: Gerstmann
orcid: 0000-0002-4476-223X
citation:
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.
Physical Review Research. 2020;2(4). doi:10.1103/PhysRevResearch.2.043002'
apa: 'Schmidt, F., Kozub, A. L., Biktagirov, T., Eigner, C., Silberhorn, C., Schindlmayr,
A., Schmidt, W. G., & Gerstmann, U. (2020). Free and defect-bound (bi)polarons
in LiNbO3: Atomic structure and spectroscopic signatures from ab initio calculations.
Physical Review Research, 2(4), Article 043002. https://doi.org/10.1103/PhysRevResearch.2.043002'
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={10.1103/PhysRevResearch.2.043002},
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} }'
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.” Physical Review Research 2, no.
4 (2020). https://doi.org/10.1103/PhysRevResearch.2.043002.'
ieee: 'F. Schmidt et al., “Free and defect-bound (bi)polarons in LiNbO3:
Atomic structure and spectroscopic signatures from ab initio calculations,” Physical
Review Research, vol. 2, no. 4, Art. no. 043002, 2020, doi: 10.1103/PhysRevResearch.2.043002.'
mla: 'Schmidt, Falko, et al. “Free and Defect-Bound (Bi)Polarons in LiNbO3: Atomic
Structure and Spectroscopic Signatures from Ab Initio Calculations.” Physical
Review Research, vol. 2, no. 4, 043002, American Physical Society, 2020, doi:10.1103/PhysRevResearch.2.043002.'
short: F. Schmidt, A.L. Kozub, T. Biktagirov, C. Eigner, C. Silberhorn, A. Schindlmayr,
W.G. Schmidt, U. Gerstmann, Physical Review Research 2 (2020).
date_created: 2020-09-09T09:35:21Z
date_updated: 2023-04-20T16:06:21Z
ddc:
- '530'
department:
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '295'
- _id: '288'
- _id: '15'
- _id: '170'
- _id: '35'
- _id: '790'
doi: 10.1103/PhysRevResearch.2.043002
external_id:
isi:
- '000604206300002'
file:
- access_level: open_access
content_type: application/pdf
creator: schindlm
date_created: 2020-10-02T07:27:38Z
date_updated: 2020-10-02T07:37:24Z
description: Creative Commons Attribution 4.0 International Public License (CC BY
4.0)
file_id: '19843'
file_name: PhysRevResearch.2.043002.pdf
file_size: 1955183
relation: main_file
title: 'Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic
signatures from ab initio calculations'
file_date_updated: 2020-10-02T07:37:24Z
has_accepted_license: '1'
intvolume: ' 2'
isi: '1'
issue: '4'
language:
- iso: eng
oa: '1'
project:
- _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: '52'
name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication: Physical Review Research
publication_identifier:
eissn:
- 2643-1564
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
status: public
title: 'Free and defect-bound (bi)polarons in LiNbO3: Atomic structure and spectroscopic
signatures from ab initio calculations'
type: journal_article
user_id: '16199'
volume: 2
year: '2020'
...
---
_id: '10014'
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.
article_number: '054401'
article_type: original
author:
- first_name: Falko
full_name: Schmidt, Falko
id: '35251'
last_name: Schmidt
orcid: 0000-0002-5071-5528
- first_name: Arthur
full_name: Riefer, Arthur
last_name: Riefer
- first_name: Wolf Gero
full_name: Schmidt, Wolf Gero
id: '468'
last_name: Schmidt
orcid: 0000-0002-2717-5076
- first_name: Arno
full_name: Schindlmayr, Arno
id: '458'
last_name: Schindlmayr
orcid: 0000-0002-4855-071X
- first_name: Mirco
full_name: Imlau, Mirco
last_name: Imlau
- first_name: Florian
full_name: Dobener, Florian
last_name: Dobener
- first_name: Nils
full_name: Mengel, Nils
last_name: Mengel
- first_name: Sangam
full_name: Chatterjee, Sangam
last_name: Chatterjee
- first_name: Simone
full_name: Sanna, Simone
last_name: Sanna
citation:
ama: Schmidt F, Riefer A, Schmidt WG, et al. Quasiparticle and excitonic effects
in the optical response of KNbO3. Physical Review Materials. 2019;3(5).
doi:10.1103/PhysRevMaterials.3.054401
apa: Schmidt, F., Riefer, A., Schmidt, W. G., Schindlmayr, A., Imlau, M., Dobener,
F., Mengel, N., Chatterjee, S., & Sanna, S. (2019). Quasiparticle and excitonic
effects in the optical response of KNbO3. Physical Review Materials, 3(5),
Article 054401. https://doi.org/10.1103/PhysRevMaterials.3.054401
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={10.1103/PhysRevMaterials.3.054401},
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} }'
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.” Physical Review Materials
3, no. 5 (2019). https://doi.org/10.1103/PhysRevMaterials.3.054401.
ieee: 'F. Schmidt et al., “Quasiparticle and excitonic effects in the optical
response of KNbO3,” Physical Review Materials, vol. 3, no. 5, Art. no.
054401, 2019, doi: 10.1103/PhysRevMaterials.3.054401.'
mla: Schmidt, Falko, et al. “Quasiparticle and Excitonic Effects in the Optical
Response of KNbO3.” Physical Review Materials, vol. 3, no. 5, 054401, American
Physical Society, 2019, doi:10.1103/PhysRevMaterials.3.054401.
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).
date_created: 2019-05-29T06:55:29Z
date_updated: 2023-04-20T14:20:33Z
ddc:
- '530'
department:
- _id: '295'
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '170'
- _id: '35'
doi: 10.1103/PhysRevMaterials.3.054401
external_id:
isi:
- '000467044000003'
file:
- access_level: open_access
content_type: application/pdf
creator: schindlm
date_created: 2020-08-27T19:05:54Z
date_updated: 2020-08-30T14:34:33Z
description: © 2019 American Physical Society
file_id: '18465'
file_name: PhysRevMaterials.3.054401.pdf
file_size: 1949504
relation: main_file
title: Quasiparticle and excitonic effects in the optical response of KNbO3
file_date_updated: 2020-08-30T14:34:33Z
has_accepted_license: '1'
intvolume: ' 3'
isi: '1'
issue: '5'
language:
- iso: eng
oa: '1'
project:
- _id: '52'
name: Computing Resources Provided by the Paderborn Center for Parallel Computing
- _id: '53'
name: TRR 142
- _id: '55'
name: TRR 142 - Project Area B
- _id: '69'
name: TRR 142 - Subproject B4
- _id: '52'
name: 'PC2: Computing Resources Provided by the Paderborn Center for Parallel Computing'
publication: Physical Review Materials
publication_identifier:
eissn:
- 2475-9953
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
status: public
title: Quasiparticle and excitonic effects in the optical response of KNbO3
type: journal_article
user_id: '16199'
volume: 3
year: '2019'
...
---
_id: '10023'
abstract:
- lang: eng
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.
article_number: '3981317'
article_type: original
author:
- first_name: Falko
full_name: Schmidt, Falko
id: '35251'
last_name: Schmidt
orcid: 0000-0002-5071-5528
- first_name: Marc
full_name: Landmann, Marc
last_name: Landmann
- first_name: Eva
full_name: Rauls, Eva
last_name: Rauls
- first_name: Nicola
full_name: Argiolas, Nicola
last_name: Argiolas
- 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
- first_name: Arno
full_name: Schindlmayr, Arno
id: '458'
last_name: Schindlmayr
orcid: 0000-0002-4855-071X
citation:
ama: Schmidt F, Landmann M, Rauls E, et al. Consistent atomic geometries and electronic
structure of five phases of potassium niobate from density-functional theory.
Advances in Materials Science and Engineering. 2017;2017. doi:10.1155/2017/3981317
apa: Schmidt, F., Landmann, M., Rauls, E., Argiolas, N., Sanna, S., Schmidt, W.
G., & Schindlmayr, A. (2017). Consistent atomic geometries and electronic
structure of five phases of potassium niobate from density-functional theory.
Advances in Materials Science and Engineering, 2017, Article 3981317.
https://doi.org/10.1155/2017/3981317
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={10.1155/2017/3981317},
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} }'
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.”
Advances in Materials Science and Engineering 2017 (2017). https://doi.org/10.1155/2017/3981317.
ieee: 'F. Schmidt et al., “Consistent atomic geometries and electronic structure
of five phases of potassium niobate from density-functional theory,” Advances
in Materials Science and Engineering, vol. 2017, Art. no. 3981317, 2017, doi:
10.1155/2017/3981317.'
mla: Schmidt, Falko, et al. “Consistent Atomic Geometries and Electronic Structure
of Five Phases of Potassium Niobate from Density-Functional Theory.” Advances
in Materials Science and Engineering, vol. 2017, 3981317, Hindawi, 2017, doi:10.1155/2017/3981317.
short: F. Schmidt, M. Landmann, E. Rauls, N. Argiolas, S. Sanna, W.G. Schmidt, A.
Schindlmayr, Advances in Materials Science and Engineering 2017 (2017).
date_created: 2019-05-29T07:48:32Z
date_updated: 2025-12-05T09:58:11Z
ddc:
- '530'
department:
- _id: '295'
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '15'
- _id: '35'
- _id: '27'
doi: 10.1155/2017/3981317
external_id:
isi:
- '000394873300001'
file:
- access_level: open_access
content_type: application/pdf
creator: schindlm
date_created: 2020-08-28T09:27:19Z
date_updated: 2020-08-30T14:37:31Z
description: Creative Commons Attribution 4.0 International Public License (CC BY
4.0)
file_id: '18538'
file_name: 3981317.pdf
file_size: 985948
relation: main_file
title: Consistent atomic geometries and electronic structure of five phases of potassium
niobate from density-functional theory
file_date_updated: 2020-08-30T14:37:31Z
has_accepted_license: '1'
intvolume: ' 2017'
isi: '1'
language:
- iso: eng
oa: '1'
project:
- _id: '52'
name: Computing Resources Provided by the Paderborn Center for Parallel Computing
- _id: '53'
name: TRR 142
- _id: '55'
name: TRR 142 - Project Area B
- _id: '69'
name: TRR 142 - Subproject B4
- _id: '52'
name: Computing Resources Provided by the Paderborn Center for Parallel Computing
publication: Advances in Materials Science and Engineering
publication_identifier:
eissn:
- 1687-8442
issn:
- 1687-8434
publication_status: published
publisher: Hindawi
quality_controlled: '1'
status: public
title: Consistent atomic geometries and electronic structure of five phases of potassium
niobate from density-functional theory
type: journal_article
user_id: '16199'
volume: 2017
year: '2017'
...