Modeling polarons in density functional theory: Lessons learned from TiO2

M. Reticcioli, U. Diebold, C. Franchini

Faculty of Physics, Center for Computational Materials Science, University of Vienna, Vienna, Austria
Institut für Angewandte Physik, TU Wien, 1040 Wien, Austria
Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy

J. Phys.: Condens. Matter 34 (2022) 204006

Density functional theory (DFT) is nowadays one of the most broadly used and successful techniques to study the properties of polarons and their effects in materials. Here, we systematically analyze the aspects of the theoretical calculations that are crucial to obtain reliable predictions in agreement with the experimental observations. We focus on rutile TiO2, a prototypical polaronic compound, and compare the formation of polarons on the (110) surface and subsurface atomic layers. As expected, the parameter U used to correct the electronic correlation in the DFT + U formalism affects the resulting charge localization, local structural distortions and electronic properties of polarons. Moreover, the polaron localization can be driven to different sites by strain: due to different local environments, surface and subsurface polarons show different responses to the applied strain, with impact on the relative energy stability. An accurate description of the properties of polarons is key to understand their impact on complex phenomena and applications: as an example, we show the effects of lattice strain on the interaction between polarons and CO adsorbates.

Corresponding author: Michele Reticcioli. Reprints also available from Ulrike Diebold (diebold at iap_tuwien_ac_at).

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