Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 11: Electronic Structure Theory
O 11.4: Vortrag
Montag, 5. September 2022, 15:45–16:00, H6
Implementation of DFT+U+J and the minimum-tracking linear response method for polaron formation modeling — •Ziwei Chai1,3, Karsten Reuter3, Harald Oberhofer1,2, and Limin Liu4 — 1Chair for Theoretical Chemistry, Technische Universität München — 2Chair for Theoretical Physics VII, Universität Bayreuth, Germany — 3Fritz-Haber-Institut der Max-Planck-Gesellschaft — 4School of Physics, Beihang University
In many oxides charge carriers localize as small polarons. However, treating them with semi-local first-principles density-functional theory (DFT) tends to be a challenge usually addressed by hybrid DFT or Hubbard-corrected DFT+U. We present our implementation of DFT+U+J based on a "tensorial" representation of the subspace and the "minimum-tracking linear response method" which can determine U and J parameters from first-principles in the CP2K package. We performed systematic tests to prove the validity of the implementation.
Finally, the formation of polarons can be modeled by either breaking the symmetry of the initial structure or imposing an implicit or explicit constraining potential on the local orbital occupation. On top of our DFT+U+J implementation, we thus present the subspace occupancy-constraining potential (SOCP) approach to simulate the formation of polarons by constraining the occupancy number of the relevant local orbitals. Any polaronic configuration can thus straightforwardly be accessed without the need to explicitly break the system’s symmetry.