---
_id: '61279'
abstract:
- lang: eng
  text: Spin waves represent an important class of low-energy excitations in magnetic
    solids, which influence the thermodynamic properties and play a major role in
    technical applications, such as spintronics or magnetic data storage. Despite
    the enormous advances of ab initio simulations in materials science, quantitative
    calculations of spin-wave spectra still pose a significant challenge, because
    the collective nature of the spin dynamics requires an accurate treatment of the
    Coulomb interaction between the electrons. As a consequence, simple lattice models
    like the Heisenberg Hamiltonian are still widespread in practical investigations,
    but modern techniques like time-dependent density-functional theory or many-body
    perturbation theory also open a route to material-specific spin-wave calculations
    from first principles. Although both are in principle exact, actual implementations
    necessarily employ approximations for electronic exchange and correlation as well
    as additional numerical simplifications. In this review, we recapitulate the theoretical
    foundations of ab initio spin-wave calculations and analyze the common approximations
    that underlie present implementations. In addition, we survey the available results
    for spin-wave dispersions of various magnetic materials and compare the performance
    of different computational approaches. In this way, we provide an overview of
    the present state of the art and identify directions for further developments.
article_number: '4431'
article_type: review
author:
- first_name: Michael
  full_name: Neugum, Michael
  id: '80813'
  last_name: Neugum
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
citation:
  ama: 'Neugum M, Schindlmayr A. Ab initio calculations of spin waves: A review of
    theoretical approaches and applications. <i>Materials</i>. 2025;18(18). doi:<a
    href="https://doi.org/10.3390/ma18184431">10.3390/ma18184431</a>'
  apa: 'Neugum, M., &#38; Schindlmayr, A. (2025). Ab initio calculations of spin waves:
    A review of theoretical approaches and applications. <i>Materials</i>, <i>18</i>(18),
    Article 4431. <a href="https://doi.org/10.3390/ma18184431">https://doi.org/10.3390/ma18184431</a>'
  bibtex: '@article{Neugum_Schindlmayr_2025, title={Ab initio calculations of spin
    waves: A review of theoretical approaches and applications}, volume={18}, DOI={<a
    href="https://doi.org/10.3390/ma18184431">10.3390/ma18184431</a>}, number={184431},
    journal={Materials}, publisher={MDPI}, author={Neugum, Michael and Schindlmayr,
    Arno}, year={2025} }'
  chicago: 'Neugum, Michael, and Arno Schindlmayr. “Ab Initio Calculations of Spin
    Waves: A Review of Theoretical Approaches and Applications.” <i>Materials</i>
    18, no. 18 (2025). <a href="https://doi.org/10.3390/ma18184431">https://doi.org/10.3390/ma18184431</a>.'
  ieee: 'M. Neugum and A. Schindlmayr, “Ab initio calculations of spin waves: A review
    of theoretical approaches and applications,” <i>Materials</i>, vol. 18, no. 18,
    Art. no. 4431, 2025, doi: <a href="https://doi.org/10.3390/ma18184431">10.3390/ma18184431</a>.'
  mla: 'Neugum, Michael, and Arno Schindlmayr. “Ab Initio Calculations of Spin Waves:
    A Review of Theoretical Approaches and Applications.” <i>Materials</i>, vol. 18,
    no. 18, 4431, MDPI, 2025, doi:<a href="https://doi.org/10.3390/ma18184431">10.3390/ma18184431</a>.'
  short: M. Neugum, A. Schindlmayr, Materials 18 (2025).
date_created: 2025-09-15T16:14:59Z
date_updated: 2025-10-10T07:31:23Z
ddc:
- '530'
department:
- _id: '296'
- _id: '15'
- _id: '170'
- _id: '35'
- _id: '230'
doi: 10.3390/ma18184431
external_id:
  isi:
  - '001580599300001'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2025-09-24T07:19:36Z
  date_updated: 2025-09-24T07:19:36Z
  description: Creative Commons Attribution 4.0 International Public License (CC BY
    4.0)
  file_id: '61422'
  file_name: materials-18-04431.pdf
  file_size: 611341
  relation: main_file
  title: 'Ab initio calculations of spin waves: A review of theoretical approaches
    and applications'
file_date_updated: 2025-09-24T07:19:36Z
has_accepted_license: '1'
intvolume: '        18'
isi: '1'
issue: '18'
language:
- iso: eng
oa: '1'
publication: Materials
publication_identifier:
  eissn:
  - 1996-1944
publication_status: published
publisher: MDPI
quality_controlled: '1'
status: public
title: 'Ab initio calculations of spin waves: A review of theoretical approaches and
  applications'
type: journal_article
user_id: '458'
volume: 18
year: '2025'
...
---
_id: '60959'
abstract:
- lang: eng
  text: Miller's rule originated as an empirical relation between the nonlinear and
    linear optical coefficients of materials. It is now accepted as a useful tool
    for guiding experiments and computational materials discovery, but its theoretical
    foundation had long been limited to a derivation for the classical Lorentz model
    with a weak anharmonic perturbation. Recently, we developed a mathematical framework
    which enabled us to prove that Miller's rule is equally valid for quantum anharmonic
    oscillators, despite different dynamics due to zero-point fluctuations and further
    quantum-mechanical effects. However, our previous derivation applied only to one-dimensional
    oscillators and to the special case of second- and third-harmonic generation in
    a monochromatic electric field. Here we extend the proof to three-dimensional
    quantum anharmonic oscillators and also treat all orders of the nonlinear response
    to an arbitrary multi-frequency field. This makes the results applicable to a
    much larger range of physical systems and nonlinear optical processes. The obtained
    generalized Miller formulae rigorously express all tensor elements of the frequency-dependent
    nonlinear susceptibilities in terms of the linear susceptibility and thus allow
    a computationally inexpensive quantitative prediction of arbitrary parametric
    frequency-mixing processes from a small initial dataset.
article_number: '34'
article_type: original
author:
- first_name: Maximilian Tim
  full_name: Meyer, Maximilian Tim
  id: '77895'
  last_name: Meyer
  orcid: 0009-0003-4899-0920
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
citation:
  ama: Meyer MT, Schindlmayr A. Generalized Miller formulae for quantum anharmonic
    oscillators. <i>Dynamics</i>. 2025;5(3). doi:<a href="https://doi.org/10.3390/dynamics5030034">10.3390/dynamics5030034</a>
  apa: Meyer, M. T., &#38; Schindlmayr, A. (2025). Generalized Miller formulae for
    quantum anharmonic oscillators. <i>Dynamics</i>, <i>5</i>(3), Article 34. <a href="https://doi.org/10.3390/dynamics5030034">https://doi.org/10.3390/dynamics5030034</a>
  bibtex: '@article{Meyer_Schindlmayr_2025, title={Generalized Miller formulae for
    quantum anharmonic oscillators}, volume={5}, DOI={<a href="https://doi.org/10.3390/dynamics5030034">10.3390/dynamics5030034</a>},
    number={334}, journal={Dynamics}, publisher={MDPI}, author={Meyer, Maximilian
    Tim and Schindlmayr, Arno}, year={2025} }'
  chicago: Meyer, Maximilian Tim, and Arno Schindlmayr. “Generalized Miller Formulae
    for Quantum Anharmonic Oscillators.” <i>Dynamics</i> 5, no. 3 (2025). <a href="https://doi.org/10.3390/dynamics5030034">https://doi.org/10.3390/dynamics5030034</a>.
  ieee: 'M. T. Meyer and A. Schindlmayr, “Generalized Miller formulae for quantum
    anharmonic oscillators,” <i>Dynamics</i>, vol. 5, no. 3, Art. no. 34, 2025, doi:
    <a href="https://doi.org/10.3390/dynamics5030034">10.3390/dynamics5030034</a>.'
  mla: Meyer, Maximilian Tim, and Arno Schindlmayr. “Generalized Miller Formulae for
    Quantum Anharmonic Oscillators.” <i>Dynamics</i>, vol. 5, no. 3, 34, MDPI, 2025,
    doi:<a href="https://doi.org/10.3390/dynamics5030034">10.3390/dynamics5030034</a>.
  short: M.T. Meyer, A. Schindlmayr, Dynamics 5 (2025).
date_created: 2025-08-20T09:46:13Z
date_updated: 2025-10-10T07:29:36Z
ddc:
- '530'
department:
- _id: '296'
- _id: '230'
- _id: '15'
- _id: '170'
- _id: '35'
doi: 10.3390/dynamics5030034
external_id:
  isi:
  - '001581270200001'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2025-08-28T12:23:26Z
  date_updated: 2025-08-28T12:27:05Z
  description: Creative Commons Attribution 4.0 International Public License (CC BY
    4.0)
  file_id: '61056'
  file_name: dynamics-05-00034.pdf
  file_size: 375897
  relation: main_file
  title: Generalized Miller formulae for quantum anharmonic oscillators
file_date_updated: 2025-08-28T12:27:05Z
has_accepted_license: '1'
intvolume: '         5'
isi: '1'
issue: '3'
language:
- iso: eng
oa: '1'
publication: Dynamics
publication_identifier:
  eissn:
  - 2673-8716
publication_status: published
publisher: MDPI
quality_controlled: '1'
status: public
title: Generalized Miller formulae for quantum anharmonic oscillators
type: journal_article
user_id: '458'
volume: 5
year: '2025'
...
---
_id: '52723'
abstract:
- lang: eng
  text: Miller's rule is an empirical relation between the nonlinear and linear optical
    coefficients that applies to a large class of materials but has only been rigorously
    derived for the classical Lorentz model with a weak anharmonic perturbation. In
    this work, we extend the proof and present a detailed derivation of Miller's rule
    for an equivalent quantum-mechanical anharmonic oscillator. For this purpose,
    the classical concept of velocity-dependent damping inherent to the Lorentz model
    is replaced by an adiabatic switch-on of the external electric field, which allows
    a unified treatment of the classical and quantum-mechanical systems using identical
    potentials and fields. Although the dynamics of the resulting charge oscillations,
    and hence the induced polarizations, deviate due to the finite zero-point motion
    in the quantum-mechanical framework, we find that Miller's rule is nevertheless
    identical in both cases up to terms of first order in the anharmonicity. With
    a view to practical applications, especially in the context of ab initio calculations
    for the optical response where adiabatically switched-on fields are widely assumed,
    we demonstrate that a correct treatment of finite broadening parameters is essential
    to avoid spurious errors that may falsely suggest a violation of Miller's rule,
    and we illustrate this point by means of a numerical example.
article_number: '095001'
article_type: original
author:
- first_name: Maximilian Tim
  full_name: Meyer, Maximilian Tim
  id: '77895'
  last_name: Meyer
  orcid: 0009-0003-4899-0920
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
citation:
  ama: 'Meyer MT, Schindlmayr A. Derivation of Miller’s rule for the nonlinear optical
    susceptibility of a quantum anharmonic oscillator. <i>Journal of Physics B: Atomic,
    Molecular and Optical Physics</i>. 2024;57(9). doi:<a href="https://doi.org/10.1088/1361-6455/ad369c">10.1088/1361-6455/ad369c</a>'
  apa: 'Meyer, M. T., &#38; Schindlmayr, A. (2024). Derivation of Miller’s rule for
    the nonlinear optical susceptibility of a quantum anharmonic oscillator. <i>Journal
    of Physics B: Atomic, Molecular and Optical Physics</i>, <i>57</i>(9), Article
    095001. <a href="https://doi.org/10.1088/1361-6455/ad369c">https://doi.org/10.1088/1361-6455/ad369c</a>'
  bibtex: '@article{Meyer_Schindlmayr_2024, title={Derivation of Miller’s rule for
    the nonlinear optical susceptibility of a quantum anharmonic oscillator}, volume={57},
    DOI={<a href="https://doi.org/10.1088/1361-6455/ad369c">10.1088/1361-6455/ad369c</a>},
    number={9095001}, journal={Journal of Physics B: Atomic, Molecular and Optical
    Physics}, publisher={IOP Publishing}, author={Meyer, Maximilian Tim and Schindlmayr,
    Arno}, year={2024} }'
  chicago: 'Meyer, Maximilian Tim, and Arno Schindlmayr. “Derivation of Miller’s Rule
    for the Nonlinear Optical Susceptibility of a Quantum Anharmonic Oscillator.”
    <i>Journal of Physics B: Atomic, Molecular and Optical Physics</i> 57, no. 9 (2024).
    <a href="https://doi.org/10.1088/1361-6455/ad369c">https://doi.org/10.1088/1361-6455/ad369c</a>.'
  ieee: 'M. T. Meyer and A. Schindlmayr, “Derivation of Miller’s rule for the nonlinear
    optical susceptibility of a quantum anharmonic oscillator,” <i>Journal of Physics
    B: Atomic, Molecular and Optical Physics</i>, vol. 57, no. 9, Art. no. 095001,
    2024, doi: <a href="https://doi.org/10.1088/1361-6455/ad369c">10.1088/1361-6455/ad369c</a>.'
  mla: 'Meyer, Maximilian Tim, and Arno Schindlmayr. “Derivation of Miller’s Rule
    for the Nonlinear Optical Susceptibility of a Quantum Anharmonic Oscillator.”
    <i>Journal of Physics B: Atomic, Molecular and Optical Physics</i>, vol. 57, no.
    9, 095001, IOP Publishing, 2024, doi:<a href="https://doi.org/10.1088/1361-6455/ad369c">10.1088/1361-6455/ad369c</a>.'
  short: 'M.T. Meyer, A. Schindlmayr, Journal of Physics B: Atomic, Molecular and
    Optical Physics 57 (2024).'
date_created: 2024-03-22T08:44:39Z
date_updated: 2024-04-13T11:20:56Z
ddc:
- '530'
department:
- _id: '296'
- _id: '230'
- _id: '15'
- _id: '170'
- _id: '35'
doi: 10.1088/1361-6455/ad369c
external_id:
  isi:
  - '001196678300001'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2024-04-04T09:24:22Z
  date_updated: 2024-04-04T09:24:22Z
  description: Creative Commons Attribution 4.0 International Public License (CC BY
    4.0)
  file_id: '53204'
  file_name: Meyer_2024_J._Phys._B _At._Mol._Opt._Phys._57_095001.pdf
  file_size: 358155
  relation: main_file
  title: Derivation of Miller's rule for the nonlinear optical susceptibility of a
    quantum anharmonic oscillator
file_date_updated: 2024-04-04T09:24:22Z
has_accepted_license: '1'
intvolume: '        57'
isi: '1'
issue: '9'
language:
- iso: eng
oa: '1'
publication: 'Journal of Physics B: Atomic, Molecular and Optical Physics'
publication_identifier:
  eissn:
  - 1361-6455
  issn:
  - 0953-4075
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
status: public
title: Derivation of Miller's rule for the nonlinear optical susceptibility of a quantum
  anharmonic oscillator
type: journal_article
user_id: '458'
volume: 57
year: '2024'
...
---
_id: '26627'
abstract:
- lang: eng
  text: Many-body perturbation theory based on density-functional theory calculations
    is used to determine the quasiparticle band structures and the dielectric functions
    of the isomorphic ferroelectrics rubidium titanyl phosphate (RbTiOPO4) and potassium
    titanyl arsenide (KTiOAsO4). Self-energy corrections of more than 2 eV are found
    to widen the transport band gaps of both materials considerably to 5.3 and 5.2
    eV, respectively. At the same time, both materials are characterized by strong
    exciton binding energies of 1.4 and 1.5 eV, respectively. The solution of the
    Bethe-Salpeter equation based on the quasiparticle energies results in onsets
    of the optical absorption within the range of the measured data.
article_number: '015002'
article_type: original
author:
- first_name: Sergej
  full_name: Neufeld, Sergej
  id: '23261'
  last_name: Neufeld
- 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
citation:
  ama: 'Neufeld S, Schindlmayr A, Schmidt WG. Quasiparticle energies and optical response
    of RbTiOPO4 and KTiOAsO4. <i>Journal of Physics: Materials</i>. 2022;5(1). doi:<a
    href="https://doi.org/10.1088/2515-7639/ac3384">10.1088/2515-7639/ac3384</a>'
  apa: 'Neufeld, S., Schindlmayr, A., &#38; Schmidt, W. G. (2022). Quasiparticle energies
    and optical response of RbTiOPO4 and KTiOAsO4. <i>Journal of Physics: Materials</i>,
    <i>5</i>(1), Article 015002. <a href="https://doi.org/10.1088/2515-7639/ac3384">https://doi.org/10.1088/2515-7639/ac3384</a>'
  bibtex: '@article{Neufeld_Schindlmayr_Schmidt_2022, title={Quasiparticle energies
    and optical response of RbTiOPO4 and KTiOAsO4}, volume={5}, DOI={<a href="https://doi.org/10.1088/2515-7639/ac3384">10.1088/2515-7639/ac3384</a>},
    number={1015002}, journal={Journal of Physics: Materials}, publisher={IOP Publishing},
    author={Neufeld, Sergej and Schindlmayr, Arno and Schmidt, Wolf Gero}, year={2022}
    }'
  chicago: 'Neufeld, Sergej, Arno Schindlmayr, and Wolf Gero Schmidt. “Quasiparticle
    Energies and Optical Response of RbTiOPO4 and KTiOAsO4.” <i>Journal of Physics:
    Materials</i> 5, no. 1 (2022). <a href="https://doi.org/10.1088/2515-7639/ac3384">https://doi.org/10.1088/2515-7639/ac3384</a>.'
  ieee: 'S. Neufeld, A. Schindlmayr, and W. G. Schmidt, “Quasiparticle energies and
    optical response of RbTiOPO4 and KTiOAsO4,” <i>Journal of Physics: Materials</i>,
    vol. 5, no. 1, Art. no. 015002, 2022, doi: <a href="https://doi.org/10.1088/2515-7639/ac3384">10.1088/2515-7639/ac3384</a>.'
  mla: 'Neufeld, Sergej, et al. “Quasiparticle Energies and Optical Response of RbTiOPO4
    and KTiOAsO4.” <i>Journal of Physics: Materials</i>, vol. 5, no. 1, 015002, IOP
    Publishing, 2022, doi:<a href="https://doi.org/10.1088/2515-7639/ac3384">10.1088/2515-7639/ac3384</a>.'
  short: 'S. Neufeld, A. Schindlmayr, W.G. Schmidt, Journal of Physics: Materials
    5 (2022).'
date_created: 2021-10-20T13:00:04Z
date_updated: 2023-04-20T14:01:16Z
ddc:
- '530'
department:
- _id: '296'
- _id: '295'
- _id: '230'
- _id: '429'
- _id: '15'
- _id: '170'
- _id: '35'
doi: 10.1088/2515-7639/ac3384
external_id:
  isi:
  - '000721060500001'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2021-11-22T17:57:00Z
  date_updated: 2021-11-22T17:57:00Z
  description: Creative Commons Attribution 4.0 International Public License (CC BY
    4.0)
  file_id: '27705'
  file_name: Neufeld_2022_J._Phys._Mater._5_015002.pdf
  file_size: 2687065
  relation: main_file
  title: Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4
file_date_updated: 2021-11-22T17:57:00Z
funded_apc: '1'
has_accepted_license: '1'
intvolume: '         5'
isi: '1'
issue: '1'
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'
- _id: '168'
  name: 'TRR 142 - B07: TRR 142 - Subproject B07'
publication: 'Journal of Physics: Materials'
publication_identifier:
  eissn:
  - 2515-7639
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
status: public
title: Quasiparticle energies and optical response of RbTiOPO4 and KTiOAsO4
type: journal_article
user_id: '16199'
volume: 5
year: '2022'
...
---
_id: '29808'
abstract:
- lang: ger
  text: Dieses Format eignet sich, um zu prüfen, inwieweit Studierende Computersimulationen
    und eigene kleine Programme zur Lösung typischer Probleme ihres Fachs nutzen
    können. Wie bei Klausuren erfolgt die Bearbeitung in begrenzter Zeit und unter
    Aufsicht, wird aber am Computer durchgeführt und beinhaltet neben der Programmierung
    auch vor- und nachbereitende Aufgaben im Kontext der fachlichen Anwendung.
author:
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
citation:
  ama: 'Schindlmayr A. Programmierung und Computersimulationen. In: Gerick J, Sommer
    A, Zimmermann G, eds. <i>Kompetent Prüfungen gestalten: 60 Prüfungsformate für
    die Hochschullehre</i>. 2nd ed. Waxmann; 2022:270-274. doi:<a href="https://doi.org/10.36198/9783838558592">10.36198/9783838558592</a>'
  apa: 'Schindlmayr, A. (2022). Programmierung und Computersimulationen. In J. Gerick,
    A. Sommer, &#38; G. Zimmermann (Eds.), <i>Kompetent Prüfungen gestalten: 60 Prüfungsformate
    für die Hochschullehre</i> (2nd ed., pp. 270–274). Waxmann. <a href="https://doi.org/10.36198/9783838558592">https://doi.org/10.36198/9783838558592</a>'
  bibtex: '@inbook{Schindlmayr_2022, place={Münster}, edition={2}, title={Programmierung
    und Computersimulationen}, DOI={<a href="https://doi.org/10.36198/9783838558592">10.36198/9783838558592</a>},
    booktitle={Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre},
    publisher={Waxmann}, author={Schindlmayr, Arno}, editor={Gerick, Julia and Sommer,
    Angela and Zimmermann, Germo}, year={2022}, pages={270–274} }'
  chicago: 'Schindlmayr, Arno. “Programmierung und Computersimulationen.” In <i>Kompetent
    Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i>, edited by
    Julia Gerick, Angela Sommer, and Germo Zimmermann, 2nd ed., 270–74. Münster: Waxmann,
    2022. <a href="https://doi.org/10.36198/9783838558592">https://doi.org/10.36198/9783838558592</a>.'
  ieee: 'A. Schindlmayr, “Programmierung und Computersimulationen,” in <i>Kompetent
    Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i>, 2nd ed., J.
    Gerick, A. Sommer, and G. Zimmermann, Eds. Münster: Waxmann, 2022, pp. 270–274.'
  mla: 'Schindlmayr, Arno. “Programmierung und Computersimulationen.” <i>Kompetent
    Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre</i>, edited by
    Julia Gerick et al., 2nd ed., Waxmann, 2022, pp. 270–74, doi:<a href="https://doi.org/10.36198/9783838558592">10.36198/9783838558592</a>.'
  short: 'A. Schindlmayr, in: J. Gerick, A. Sommer, G. Zimmermann (Eds.), Kompetent
    Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre, 2nd ed., Waxmann,
    Münster, 2022, pp. 270–274.'
date_created: 2022-02-11T11:13:37Z
date_updated: 2023-04-20T14:55:58Z
department:
- _id: '296'
- _id: '170'
- _id: '15'
- _id: '35'
doi: 10.36198/9783838558592
edition: '2'
editor:
- first_name: Julia
  full_name: Gerick, Julia
  last_name: Gerick
- first_name: Angela
  full_name: Sommer, Angela
  last_name: Sommer
- first_name: Germo
  full_name: Zimmermann, Germo
  last_name: Zimmermann
language:
- iso: ger
page: 270-274
place: Münster
publication: 'Kompetent Prüfungen gestalten: 60 Prüfungsformate für die Hochschullehre'
publication_identifier:
  eisbn:
  - '9783838558592'
  isbn:
  - '9783825258597'
publication_status: published
publisher: Waxmann
quality_controlled: '1'
status: public
title: Programmierung und Computersimulationen
type: book_chapter
user_id: '16199'
year: '2022'
...
---
_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. <i>Crystals</i>.
    2022;12(11). doi:<a href="https://doi.org/10.3390/cryst12111586">10.3390/cryst12111586</a>
  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>
  bibtex: '@article{Schmidt_Kozub_Gerstmann_Schmidt_Schindlmayr_2022, title={A density-functional
    theory study of hole and defect-bound exciton polarons in lithium niobate}, volume={12},
    DOI={<a href="https://doi.org/10.3390/cryst12111586">10.3390/cryst12111586</a>},
    number={111586}, journal={Crystals}, publisher={MDPI AG}, author={Schmidt, Falko
    and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt, Wolf Gero and Schindlmayr,
    Arno}, year={2022} }'
  chicago: Schmidt, Falko, Agnieszka L. Kozub, Uwe Gerstmann, Wolf Gero Schmidt, and
    Arno Schindlmayr. “A Density-Functional Theory Study of Hole and Defect-Bound
    Exciton Polarons in Lithium Niobate.” <i>Crystals</i> 12, no. 11 (2022). <a href="https://doi.org/10.3390/cryst12111586">https://doi.org/10.3390/cryst12111586</a>.
  ieee: 'F. Schmidt, A. L. Kozub, U. Gerstmann, W. G. Schmidt, and A. Schindlmayr,
    “A density-functional theory study of hole and defect-bound exciton polarons in
    lithium niobate,” <i>Crystals</i>, vol. 12, no. 11, Art. no. 1586, 2022, doi:
    <a href="https://doi.org/10.3390/cryst12111586">10.3390/cryst12111586</a>.'
  mla: Schmidt, Falko, et al. “A Density-Functional Theory Study of Hole and Defect-Bound
    Exciton Polarons in Lithium Niobate.” <i>Crystals</i>, vol. 12, no. 11, 1586,
    MDPI AG, 2022, doi:<a href="https://doi.org/10.3390/cryst12111586">10.3390/cryst12111586</a>.
  short: F. Schmidt, A.L. Kozub, U. Gerstmann, W.G. Schmidt, A. Schindlmayr, Crystals
    12 (2022).
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. <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>'
  apa: 'Schmidt, F., Kozub, A. L., Gerstmann, U., Schmidt, W. G., &#38; Schindlmayr,
    A. (2022). Electron polarons in lithium niobate: Charge localization, lattice
    deformation, and optical response. In G. Corradi &#38; L. Kovács (Eds.), <i>New
    Trends in Lithium Niobate: From Bulk to Nanocrystals</i> (pp. 231–248). MDPI.
    <a href="https://doi.org/10.3390/books978-3-0365-3339-1">https://doi.org/10.3390/books978-3-0365-3339-1</a>'
  bibtex: '@inbook{Schmidt_Kozub_Gerstmann_Schmidt_Schindlmayr_2022, place={Basel},
    title={Electron polarons in lithium niobate: Charge localization, lattice deformation,
    and optical response}, DOI={<a href="https://doi.org/10.3390/books978-3-0365-3339-1">10.3390/books978-3-0365-3339-1</a>},
    booktitle={New Trends in Lithium Niobate: From Bulk to Nanocrystals}, publisher={MDPI},
    author={Schmidt, Falko and Kozub, Agnieszka L. and Gerstmann, Uwe and Schmidt,
    Wolf Gero and Schindlmayr, Arno}, editor={Corradi, Gábor and Kovács, László},
    year={2022}, pages={231–248} }'
  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.'
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.
    <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} }'
  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>.'
  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>.'
  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. <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>
  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>
  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} }'
  chicago: Bidaraguppe Ramesh, Nithin, Falko Schmidt, and Arno Schindlmayr. “Lattice
    Parameters and Electronic Band Gap of Orthorhombic Potassium Sodium Niobate K0.5Na0.5NbO3
    from Density-Functional Theory.” <i>The European Physical Journal B</i> 94, no.
    8 (2021). <a href="https://doi.org/10.1140/epjb/s10051-021-00179-8">https://doi.org/10.1140/epjb/s10051-021-00179-8</a>.
  ieee: 'N. Bidaraguppe Ramesh, F. Schmidt, and A. Schindlmayr, “Lattice parameters
    and electronic band gap of orthorhombic potassium sodium niobate K0.5Na0.5NbO3
    from density-functional theory,” <i>The European Physical Journal B</i>, vol.
    94, no. 8, Art. no. 169, 2021, doi: <a href="https://doi.org/10.1140/epjb/s10051-021-00179-8">10.1140/epjb/s10051-021-00179-8</a>.'
  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).
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: '22761'
article_number: '039901'
author:
- first_name: Christoph
  full_name: Friedrich, Christoph
  last_name: Friedrich
- first_name: Stefan
  full_name: Blügel, Stefan
  last_name: Blügel
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
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>'
  apa: 'Friedrich, C., Blügel, S., &#38; Schindlmayr, A. (2021). Erratum: Efficient
    implementation of the GW approximation within the all-electron FLAPW method [Phys.
    Rev. B 81, 125102 (2010)]. <i>Physical Review B</i>, <i>104</i>(3), Article 039901.
    <a href="https://doi.org/10.1103/PhysRevB.104.039901">https://doi.org/10.1103/PhysRevB.104.039901</a>'
  bibtex: '@article{Friedrich_Blügel_Schindlmayr_2021, title={Erratum: Efficient implementation
    of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81,
    125102 (2010)]}, volume={104}, DOI={<a href="https://doi.org/10.1103/PhysRevB.104.039901">10.1103/PhysRevB.104.039901</a>},
    number={3039901}, journal={Physical Review B}, publisher={American Physical Society},
    author={Friedrich, Christoph and Blügel, Stefan and Schindlmayr, Arno}, year={2021}
    }'
  chicago: 'Friedrich, Christoph, Stefan Blügel, and Arno Schindlmayr. “Erratum: Efficient
    Implementation of the GW Approximation within the All-Electron FLAPW Method [Phys.
    Rev. B 81, 125102 (2010)].” <i>Physical Review B</i> 104, no. 3 (2021). <a href="https://doi.org/10.1103/PhysRevB.104.039901">https://doi.org/10.1103/PhysRevB.104.039901</a>.'
  ieee: 'C. Friedrich, S. Blügel, and A. Schindlmayr, “Erratum: Efficient implementation
    of the GW approximation within the all-electron FLAPW method [Phys. Rev. B 81,
    125102 (2010)],” <i>Physical Review B</i>, vol. 104, no. 3, Art. no. 039901, 2021,
    doi: <a href="https://doi.org/10.1103/PhysRevB.104.039901">10.1103/PhysRevB.104.039901</a>.'
  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>.'
  short: C. Friedrich, S. Blügel, A. Schindlmayr, Physical Review B 104 (2021).
date_created: 2021-07-15T19:59:00Z
date_updated: 2023-04-20T14:57:09Z
ddc:
- '530'
department:
- _id: '296'
- _id: '15'
- _id: '170'
doi: 10.1103/PhysRevB.104.039901
external_id:
  isi:
  - '000671587300006'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2021-07-15T20:16:55Z
  date_updated: 2021-07-15T20:16:55Z
  description: © 2021 American Physical Society
  file_id: '22763'
  file_name: PhysRevB.104.039901.pdf
  file_size: 180926
  relation: main_file
  title: 'Erratum: Efficient implementation of the GW approximation within the all-electron
    FLAPW method [Phys. Rev. B 81, 125102 (2010)]'
file_date_updated: 2021-07-15T20:16:55Z
has_accepted_license: '1'
intvolume: '       104'
isi: '1'
issue: '3'
language:
- iso: eng
oa: '1'
publication: Physical Review B
publication_identifier:
  eissn:
  - 2469-9969
  issn:
  - 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
  record:
  - id: '18558'
    relation: other
    status: public
status: public
title: 'Erratum: Efficient implementation of the GW approximation within the all-electron
  FLAPW method [Phys. Rev. B 81, 125102 (2010)]'
type: journal_article
user_id: '16199'
volume: 104
year: '2021'
...
---
_id: '23418'
abstract:
- lang: eng
  text: Density-functional theory within a Berry-phase formulation of the dynamical
    polarization is used to determine the second-order susceptibility χ(2) of lithium
    niobate (LiNbO3). Defect trapped polarons and bipolarons are found to strongly
    enhance the nonlinear susceptibility of the material, in particular if localized
    at NbV–VLi defect pairs. This is essentially a consequence of the polaronic excitation
    resulting in relaxation-induced gap states. The occupation of these levels leads
    to strongly enhanced χ(2) coefficients and allows for the spatial and transient
    modification of the second-harmonic generation of macroscopic samples.
article_type: original
author:
- first_name: Agnieszka L.
  full_name: Kozub, Agnieszka L.
  id: '77566'
  last_name: Kozub
  orcid: https://orcid.org/0000-0001-6584-0201
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
- 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
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>
  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>
  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} }'
  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>.'
  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>.
  short: A.L. Kozub, A. Schindlmayr, U. Gerstmann, W.G. Schmidt, Physical Review B
    104 (2021) 174110.
date_created: 2021-08-16T19:09:46Z
date_updated: 2023-04-21T11:15:30Z
ddc:
- '530'
department:
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '295'
- _id: '15'
- _id: '170'
- _id: '790'
doi: 10.1103/PhysRevB.104.174110
external_id:
  arxiv:
  - '2106.01145'
  isi:
  - '000720931400007'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2021-11-18T20:49:19Z
  date_updated: 2021-11-18T20:49:19Z
  description: © 2021 American Physical Society
  file_id: '27577'
  file_name: PhysRevB.104.174110.pdf
  file_size: 804012
  relation: main_file
  title: Polaronic enhancement of second-harmonic generation in lithium niobate
file_date_updated: 2021-11-18T20:49:19Z
has_accepted_license: '1'
intvolume: '       104'
isi: '1'
language:
- iso: eng
oa: '1'
page: '174110'
project:
- _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 B
publication_identifier:
  eissn:
  - 2469-9969
  issn:
  - 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
status: public
title: Polaronic enhancement of second-harmonic generation in lithium niobate
type: journal_article
user_id: '171'
volume: 104
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.
    <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>'
  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>'
  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} }'
  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>.'
  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>.'
  mla: 'Schmidt, Falko, et al. “Free and Defect-Bound (Bi)Polarons in LiNbO3: Atomic
    Structure and Spectroscopic Signatures from Ab Initio Calculations.” <i>Physical
    Review Research</i>, vol. 2, no. 4, 043002, American Physical Society, 2020, doi:<a
    href="https://doi.org/10.1103/PhysRevResearch.2.043002">10.1103/PhysRevResearch.2.043002</a>.'
  short: F. Schmidt, A.L. Kozub, T. Biktagirov, C. Eigner, C. Silberhorn, A. Schindlmayr,
    W.G. Schmidt, U. Gerstmann, Physical Review Research 2 (2020).
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. <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>
  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>
  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} }'
  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>.
  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>.'
  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).
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: '13365'
abstract:
- lang: eng
  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.'
article_type: original
author:
- first_name: Sergej
  full_name: Neufeld, Sergej
  id: '23261'
  last_name: Neufeld
- first_name: Adriana
  full_name: Bocchini, Adriana
  id: '58349'
  last_name: Bocchini
  orcid: https://orcid.org/0000-0002-2134-3075
- first_name: Uwe
  full_name: Gerstmann, Uwe
  id: '171'
  last_name: Gerstmann
  orcid: 0000-0002-4476-223X
- 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
citation:
  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>'
  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>'
  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} }'
  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>.'
  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.'
date_created: 2019-09-19T14:34:16Z
date_updated: 2023-04-21T11:36:12Z
ddc:
- '530'
department:
- _id: '296'
- _id: '295'
- _id: '230'
- _id: '429'
- _id: '170'
- _id: '35'
doi: 10.1088/2515-7639/ab29ba
external_id:
  isi:
  - '000560410300003'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2020-08-28T09:07:18Z
  date_updated: 2020-08-30T14:29:27Z
  description: Creative Commons Attribution 3.0 Unported Public License (CC BY 3.0)
  file_id: '18535'
  file_name: Neufeld_2019_J._Phys._Mater._2_045003.pdf
  file_size: 1481174
  relation: main_file
  title: Potassium titanyl phosphate (KTP) quasiparticle energies and optical response
file_date_updated: 2020-08-30T14:29:27Z
has_accepted_license: '1'
intvolume: '         2'
isi: '1'
language:
- iso: eng
oa: '1'
page: '045003'
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: 'Journal of Physics: Materials'
publication_identifier:
  eissn:
  - 2515-7639
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
status: public
title: Potassium titanyl phosphate (KTP) quasiparticle energies and optical response
type: journal_article
user_id: '171'
volume: 2
year: '2019'
...
---
_id: '13410'
article_number: '019902'
author:
- first_name: Michael
  full_name: Friedrich, Michael
  last_name: Friedrich
- first_name: Wolf Gero
  full_name: Schmidt, Wolf Gero
  id: '468'
  last_name: Schmidt
  orcid: 0000-0002-2717-5076
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
- first_name: Simone
  full_name: Sanna, Simone
  last_name: Sanna
citation:
  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>'
  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>'
  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} }'
  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.'
  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).
date_created: 2019-09-20T11:28:23Z
date_updated: 2025-12-05T10:07:07Z
ddc:
- '530'
department:
- _id: '295'
- _id: '296'
- _id: '230'
- _id: '429'
doi: 10.1103/PhysRevMaterials.2.019902
external_id:
  isi:
  - '000419778500006'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2020-08-28T09:11:59Z
  date_updated: 2020-08-30T14:34:54Z
  description: © 2018 American Physical Society
  file_id: '18536'
  file_name: PhysRevMaterials.2.019902.pdf
  file_size: 178961
  relation: main_file
  title: 'Erratum: Optical properties of titanium-doped lithium niobate from time-dependent
    density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]'
file_date_updated: 2020-08-30T14:34:54Z
has_accepted_license: '1'
intvolume: '         2'
isi: '1'
issue: '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: '68'
  name: TRR 142 - Subproject B3
- _id: '69'
  name: TRR 142 - Subproject B4
publication: Physical Review Materials
publication_identifier:
  eissn:
  - 2475-9953
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
  record:
  - id: '10021'
    relation: other
    status: public
status: public
title: 'Erratum: Optical properties of titanium-doped lithium niobate from time-dependent
  density-functional theory [Phys. Rev. Materials 1, 034401 (2017)]'
type: journal_article
user_id: '458'
volume: 2
year: '2018'
...
---
_id: '18466'
abstract:
- lang: eng
  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.
article_number: '3732892'
article_type: original
author:
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
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>
  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>
  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} }'
  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>.'
  mla: Schindlmayr, Arno. “Exact Formulation of the Transverse Dynamic Spin Susceptibility
    as an Initial-Value Problem.” <i>Advances in Mathematical Physics</i>, vol. 2018,
    3732892, Hindawi, 2018, doi:<a href="https://doi.org/10.1155/2018/3732892">10.1155/2018/3732892</a>.
  short: A. Schindlmayr, Advances in Mathematical Physics 2018 (2018).
date_created: 2020-08-27T19:18:34Z
date_updated: 2025-12-16T08:04:17Z
ddc:
- '530'
department:
- _id: '296'
- _id: '35'
- _id: '15'
- _id: '170'
- _id: '230'
doi: 10.1155/2018/3732892
external_id:
  isi:
  - '000422773000001'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2020-08-28T09:18:25Z
  date_updated: 2020-08-30T14:31:38Z
  description: Creative Commons Attribution 4.0 International Public License (CC BY
    4.0)
  file_id: '18537'
  file_name: 3732892.pdf
  file_size: 294410
  relation: main_file
  title: Exact formulation of the transverse dynamic spin susceptibility as an initial-value
    problem
file_date_updated: 2020-08-30T14:31:38Z
has_accepted_license: '1'
intvolume: '      2018'
isi: '1'
language:
- iso: eng
oa: '1'
publication: Advances in Mathematical Physics
publication_identifier:
  eissn:
  - 1687-9139
  issn:
  - 1687-9120
publication_status: published
publisher: Hindawi
quality_controlled: '1'
status: public
title: Exact formulation of the transverse dynamic spin susceptibility as an initial-value
  problem
type: journal_article
user_id: '16199'
volume: 2018
year: '2018'
...
---
_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.
    <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>
  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>
  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} }'
  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>.'
  mla: Schmidt, Falko, et al. “Consistent Atomic Geometries and Electronic Structure
    of Five Phases of Potassium Niobate from Density-Functional Theory.” <i>Advances
    in Materials Science and Engineering</i>, vol. 2017, 3981317, Hindawi, 2017, doi:<a
    href="https://doi.org/10.1155/2017/3981317">10.1155/2017/3981317</a>.
  short: F. Schmidt, M. Landmann, E. Rauls, N. Argiolas, S. Sanna, W.G. Schmidt, A.
    Schindlmayr, Advances in Materials Science and Engineering 2017 (2017).
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'
...
---
_id: '10021'
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.
article_number: '034401'
article_type: original
author:
- first_name: Michael
  full_name: Friedrich, Michael
  last_name: Friedrich
- first_name: Wolf Gero
  full_name: Schmidt, Wolf Gero
  id: '468'
  last_name: Schmidt
  orcid: 0000-0002-2717-5076
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
- first_name: Simone
  full_name: Sanna, Simone
  last_name: Sanna
citation:
  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} }'
  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>.
  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>.'
  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).
date_created: 2019-05-29T07:42:33Z
date_updated: 2025-12-05T10:07:07Z
ddc:
- '530'
department:
- _id: '295'
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '35'
- _id: '27'
doi: 10.1103/PhysRevMaterials.1.034401
external_id:
  isi:
  - '000416562300001'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2020-08-27T19:39:54Z
  date_updated: 2020-08-30T14:36:11Z
  description: © 2017 American Physical Society
  file_id: '18467'
  file_name: PhysRevMaterials.1.034401.pdf
  file_size: 708075
  relation: main_file
  title: Optical properties of titanium-doped lithium niobate from time-dependent
    density-functional theory
file_date_updated: 2020-08-30T14:36:11Z
has_accepted_license: '1'
intvolume: '         1'
isi: '1'
issue: '3'
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: '68'
  name: TRR 142 - Subproject B3
publication: Physical Review Materials
publication_identifier:
  issn:
  - 2475-9953
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
  record:
  - id: '13410'
    relation: other
    status: public
status: public
title: Optical properties of titanium-doped lithium niobate from time-dependent density-functional
  theory
type: journal_article
user_id: '16199'
volume: 1
year: '2017'
...
---
_id: '13416'
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.'
article_number: '054406'
article_type: original
author:
- first_name: Michael
  full_name: Friedrich, Michael
  last_name: Friedrich
- first_name: Wolf Gero
  full_name: Schmidt, Wolf Gero
  id: '468'
  last_name: Schmidt
  orcid: 0000-0002-2717-5076
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
- first_name: Simone
  full_name: Sanna, Simone
  last_name: Sanna
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>
  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>
  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} }'
  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>.'
  mla: Friedrich, Michael, et al. “Polaron Optical Absorption in Congruent Lithium
    Niobate from Time-Dependent Density-Functional Theory.” <i>Physical Review Materials</i>,
    vol. 1, no. 5, 054406, American Physical Society, 2017, doi:<a href="https://doi.org/10.1103/PhysRevMaterials.1.054406">10.1103/PhysRevMaterials.1.054406</a>.
  short: M. Friedrich, W.G. Schmidt, A. Schindlmayr, S. Sanna, Physical Review Materials
    1 (2017).
date_created: 2019-09-20T11:54:25Z
date_updated: 2025-12-05T10:14:23Z
ddc:
- '530'
department:
- _id: '296'
- _id: '295'
- _id: '230'
- _id: '429'
- _id: '35'
- _id: '15'
- _id: '27'
doi: 10.1103/PhysRevMaterials.1.054406
external_id:
  isi:
  - '000416586100003'
file:
- access_level: open_access
  content_type: application/pdf
  creator: schindlm
  date_created: 2020-08-27T19:43:49Z
  date_updated: 2020-08-30T14:38:50Z
  description: © 2017 American Physical Society
  file_id: '18468'
  file_name: PhysRevMaterials.1.054406.pdf
  file_size: 1417182
  relation: main_file
  title: Polaron optical absorption in congruent lithium niobate from time-dependent
    density-functional theory
file_date_updated: 2020-08-30T14:38:50Z
has_accepted_license: '1'
intvolume: '         1'
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: '68'
  name: TRR 142 - Subproject B3
- _id: '69'
  name: TRR 142 - Subproject B4
publication: Physical Review Materials
publication_identifier:
  eissn:
  - 2475-9953
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
status: public
title: Polaron optical absorption in congruent lithium niobate from time-dependent
  density-functional theory
type: journal_article
user_id: '16199'
volume: 1
year: '2017'
...
---
_id: '7481'
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.
article_number: '215702'
article_type: original
author:
- first_name: Arthur
  full_name: Riefer, Arthur
  last_name: Riefer
- first_name: Nils
  full_name: Weber, Nils
  last_name: Weber
- first_name: Johannes
  full_name: Mund, Johannes
  last_name: Mund
- first_name: Dmitri R.
  full_name: Yakovlev, Dmitri R.
  last_name: Yakovlev
- first_name: Manfred
  full_name: Bayer, Manfred
  last_name: Bayer
- first_name: Arno
  full_name: Schindlmayr, Arno
  id: '458'
  last_name: Schindlmayr
  orcid: 0000-0002-4855-071X
- first_name: Cedrik
  full_name: Meier, Cedrik
  id: '20798'
  last_name: Meier
  orcid: https://orcid.org/0000-0002-3787-3572
- first_name: Wolf Gero
  full_name: Schmidt, Wolf Gero
  id: '468'
  last_name: Schmidt
  orcid: 0000-0002-2717-5076
citation:
  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>'
  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>'
  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} }'
  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>.'
  mla: 'Riefer, Arthur, et al. “Zn–VI Quasiparticle Gaps and Optical Spectra from
    Many-Body Calculations.” <i>Journal of Physics: Condensed Matter</i>, vol. 29,
    no. 21, 215702, IOP Publishing, 2017, doi:<a href="https://doi.org/10.1088/1361-648x/aa6b2a">10.1088/1361-648x/aa6b2a</a>.'
  short: 'A. Riefer, N. Weber, J. Mund, D.R. Yakovlev, M. Bayer, A. Schindlmayr, C.
    Meier, W.G. Schmidt, Journal of Physics: Condensed Matter 29 (2017).'
date_created: 2019-02-04T13:46:58Z
date_updated: 2025-12-16T11:07:33Z
ddc:
- '530'
department:
- _id: '287'
- _id: '295'
- _id: '296'
- _id: '230'
- _id: '429'
- _id: '35'
- _id: '15'
- _id: '170'
- _id: '429'
- _id: '27'
doi: 10.1088/1361-648x/aa6b2a
external_id:
  isi:
  - '000400093100001'
  pmid:
  - '28374685'
file:
- access_level: closed
  content_type: application/pdf
  creator: schindlm
  date_created: 2020-08-28T14:01:15Z
  date_updated: 2020-08-30T14:34:08Z
  description: © 2017 IOP Publishing Ltd
  file_id: '18574'
  file_name: Riefer_2017_J._Phys. _Condens._Matter_29_215702.pdf
  file_size: 2551657
  relation: main_file
  title: Zn–VI quasiparticle gaps and optical spectra from many-body calculations
file_date_updated: 2020-08-30T14:34:08Z
has_accepted_license: '1'
intvolume: '        29'
isi: '1'
issue: '21'
language:
- iso: eng
pmid: '1'
project:
- _id: '53'
  name: TRR 142
- _id: '55'
  name: TRR 142 - Project Area B
- _id: '66'
  name: TRR 142 - Subproject B1
- _id: '69'
  name: TRR 142 - Subproject B4
- _id: '52'
  name: Computing Resources Provided by the Paderborn Center for Parallel Computing
publication: 'Journal of Physics: Condensed Matter'
publication_identifier:
  eissn:
  - 1361-648X
  issn:
  - 0953-8984
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
status: public
title: Zn–VI quasiparticle gaps and optical spectra from many-body calculations
type: journal_article
user_id: '16199'
volume: 29
year: '2017'
...
