Electron-electron correlations and structural, spectral and polarization properties of tetragonal BaTiO3

Naseem Ud Din; Tao Jiang; Shima Gholam Mirzaeimoghadar; Michael Chini; Volodymyr Turkowski

doi:10.1088/1361-648X/abaa81

Electron-electron correlations and structural, spectral and polarization properties of tetragonal BaTiO₃

J Phys Condens Matter. 2020 Jul 29. doi: 10.1088/1361-648X/abaa81. Online ahead of print.

Authors

Naseem Ud Din¹, Tao Jiang², Shima Gholam Mirzaeimoghadar³, Michael Chini⁴, Volodymyr Turkowski⁵

Affiliations

¹ Physics, University of Central Florida, Orlando, Florida, 32816-2368, UNITED STATES.
² Physics, University of Central Florida, Orlando, Florida, UNITED STATES.
³ Department of Physics, University of Central Florida, Orlando, Florida, UNITED STATES.
⁴ Department of Physics, University of Central Florida, Bldg 121, PS430, 4000 Central Florida Blvd, Orlando, Florida, 32816, UNITED STATES.
⁵ Department of Physics, University of Central Florida, 0 Central Florida Blvd. Building, 121 PS 460, Orlando, Florida, FL 32816-2325, UNITED STATES.

PMID: 32726762
DOI: 10.1088/1361-648X/abaa81

Abstract

To analyze the role of electron-electron correlation effects in structural (local-geometry), spectral and polarization properties of tetragonal BaTiO3 we apply DFT+U approach. We demonstrate that the system properties drastically change when the value of the local Coulomb repulsion U crosses the critical value U_c ≈ 7 eV. In particular, the correlation effects cause a change of the ratio of the in-plane and inter-plane Ti-O bond lengths, which results in a flip of the order of the Ti d-bands and change of the polarizability of the system. Since the exact value of U in BaTiO3 is unknown, we discuss how the obtained results may be revealed in experimental data, especially in the optical response and ultrafast charge dynamics, where effective U is dynamically tuned.

Keywords: DFT+U; electron-electron correlation; spectral and polarization properties.