Ryan Requist - Reduced formula for the macroscopic polarization including quantum Fluctuations
- Date: Sep 6, 2017
- Time: 11:00 AM - 12:00 PM (Local Time Germany)
- Speaker: Ryan Requist
- MPI für Microstruktur Physik Halle, Germany
- Location: CFEL (Bldg. 99)
- Room: Seminar Room III, EG.080
- Host: 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.