Ryan Requist - Reduced formula for the macroscopic polarization including quantum Fluctuations
- Datum: 06.09.2017
- Uhrzeit: 11:00 - 12:00
- Vortragende(r): Ryan Requist
- MPI für Microstruktur Physik Halle, Germany
- Ort: CFEL (Bldg. 99)
- Raum: Seminar Room III, EG.080
- Gastgeber: Angel Rubio
In this talk, I introduce a novel many-body Berry phase formula for the macroscopic polarization that maintains the simplicity of the King-Smith--Vanderbilt formula while accounting for genuine quantum fluctuations. The polarization is approximated by a sum of natural orbital geometric phases with fractional occupation numbers accounting for the dominant quantum fluctuations.
Numerical exact diagonalization calculations for the Rice-Mele-Hubbard model demonstrate that the formula accurately reproduces the exact polarization throughout the phase diagram, including the vicinity of the band insulator-Mott insulator quantum phase transition. As a final example, I show that the theory can be used to calculate topological invariants in interacting systems.