Ab initio functional-independent calculations of the clamped Pockels tensor of tetragonal barium titanate

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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:creator>de Mestral, Virginie</dc:creator>
  <dc:creator>Bastonero, Lorenzo</dc:creator>
  <dc:creator>Kotiuga, Michele</dc:creator>
  <dc:creator>Mladenovic, Marko</dc:creator>
  <dc:creator>Marzari, Nicola</dc:creator>
  <dc:creator>Luisier, Mathieu</dc:creator>
  <dc:date>2025-04-11</dc:date>
  <dc:description>We present an ab initio method to calculate the clamped Pockels tensor of ferroelectric materials from density-functional theory (DFT), the modern theory of polarization exploiting the electric-enthalpy functional, and automated first- and second-order finite-difference derivatives of the polarizations and the Hellmann-Feynman forces. Thanks to the functional-independent capabilities of our approach, we can determine the Pockels tensor of tetragonal barium titanate (BTO) beyond the local density approximation (LDA), with arbitrary exchange-correlation (XC) functionals, for example, PBEsol. The latter, together with RRKJ ultra-soft pseudo-potentials (PP) and a supercell exhibiting local titanium off-centering, enables us to stabilize the negative optical phonon modes encountered in tetragonal BTO when LDA and norm-conserving PP are combined. As a result, the correct value range of r51, the largest experimental Pockels coefficient of BTO, is recovered. We also reveal that r51 increases with decreasing titanium off-centering for this material. The lessons learned from the structural, dielectric, and vibrational investigations of BTO will be essential to design next-generation electro-optical modulators based on the Pockels effect.</dc:description>
  <dc:identifier>https://materialscloud-archive-failover.cineca.it/record/2025.57</dc:identifier>
  <dc:identifier>doi:10.24435/materialscloud:9p-tz</dc:identifier>
  <dc:identifier>mcid:2025.57</dc:identifier>
  <dc:identifier>oai:materialscloud.org:2633</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>Materials Cloud</dc:publisher>
  <dc:rights>info:eu-repo/semantics/openAccess</dc:rights>
  <dc:rights>Creative Commons Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/legalcode</dc:rights>
  <dc:subject>Pockels</dc:subject>
  <dc:subject>barium titanate</dc:subject>
  <dc:subject>aiida-vibroscopy</dc:subject>
  <dc:subject>ab initio</dc:subject>
  <dc:subject>imaginary phonons</dc:subject>
  <dc:subject>electro-optics</dc:subject>
  <dc:subject>density-functional theory</dc:subject>
  <dc:title>Ab initio functional-independent calculations of the clamped Pockels tensor of tetragonal barium titanate</dc:title>
  <dc:type>Dataset</dc:type>
</oai_dc:dc>