Virginie de Mestral^1*, Lorenzo Bastonero², Michele Kotiuga^3,4, Marko Mladenovic¹, Nicola Marzari^3,2,5, Mathieu Luisier¹

1 Integrated Systems Laboratory, ETH Zurich, Zurich, Switzerland

2 U Bremen Excellence Chair, Bremen Center for Computational Materials Science, MAPEX Center for Materials and Processes, University of Bremen, D-28359 Bremen, Germany

3 Theory and Simulation of Materials (THEOS), and National Centre for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland

4 Materials Design SARL, Montrouge, France

5 Laboratory for Materials Simulations, Paul Scherrer Institut, 5232, Villigen PSI

* Corresponding authors emails: vdemestral@iis.ee.ethz.ch

DOI10.24435/materialscloud:9p-tz [version v1]

Publication date: Apr 11, 2025

How to cite this record

Virginie de Mestral, Lorenzo Bastonero, Michele Kotiuga, Marko Mladenovic, Nicola Marzari, Mathieu Luisier, Ab initio functional-independent calculations of the clamped Pockels tensor of tetragonal barium titanate, Materials Cloud Archive 2025.57 (2025), https://doi.org/10.24435/materialscloud:9p-tz

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.

Materials Cloud sections using this data

Files

File name	Size	Description
pockels.aiida MD5md5:69f82d2bd9e7e347a3b831f8040b270e Open this AiiDA archive on renkulab.io (https://renkulab.io/)	63.3 MiB	AiiDA data for the pockels tensor of BaTiO3
BTO.hubbard.zip MD5md5:61d95e30e1a01c126bb11b157aafe455	2.0 KiB	Quantum Espresso input files to reproduce the U and V Hubbard parameters calculation for tetragonal BTO. This folder also contains the optimum U and V output values.
README.md MD5md5:fb5dfa89bb0bce5384e017a02500a5af	3.1 KiB	Instructions

License

Files and data are licensed under the terms of the following license: Creative Commons Attribution 4.0 International.
Metadata, except for email addresses, are licensed under the Creative Commons Attribution Share-Alike 4.0 International license.

External references

Keywords

Pockels barium titanate aiida-vibroscopy ab initio imaginary phonons electro-optics density-functional theory