Berlin 2018 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 59: Topological Insulators I (joint session TT/MA)
TT 59.5: Vortrag
Mittwoch, 14. März 2018, 12:45–13:00, A 053
Reduced many-body formulas for the macroscopic polarization and topological charge pumping — •Ryan Requist1 and Eberhard K. U. Gross1,2 — 1Max Planck Institute of Microstructure Physics, Halle, Germany — 2Fritz Haber Center for Molecular Dynamics, Jerusalem, Israel
In ab initio materials research, topological invariants and the macroscopic polarization are usually calculated in terms of an effective single-particle Kohn-Sham band structure, an approach which may give incorrect results even if the exact exchange-correlation potential is used. We propose a simple natural orbital geometric phase formula for the macroscopic polarization and verify that it accurately reproduces the polarization in the Rice-Mele-Hubbard model in strongly and weakly correlated regimes. An analogous formula based on a one-body reduced Berry curvature very accurately predicts the critical Hubbard interaction at which Thouless charge pumping is quenched. We discuss strategies for ab initio calculations of natural orbital geometric phases and the possibility of extending the approach to other topological invariants in correlated materials.