# Berlin 2015 – wissenschaftliches Programm

## Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

# TT: Fachverband Tiefe Temperaturen

## TT 71: Correlated Electrons: Poster Session

### TT 71.64: Poster

### Mittwoch, 18. März 2015, 15:00–18:00, Poster B

**Enforcing conservation laws in nonequilibrium cluster perturbation theory** — •Christian Gramsch and Michael Potthoff — I. Institute for Theoretical Physics, University of Hamburg, 20355 Hamburg, Germany

Recently it has been proposed to solve the nonequilibrium Dyson equation by numerically decomposing the self-energy into its Lehmann representation [1]. This allows to replace the interaction term in the Hamiltonian by noninteracting bath degrees of freedom. In our present work we analytically construct the Lehmann representation of the self-energy for arbitrary interacting systems. For any finite system, e.g. a cluster system, the number of resulting noninteracting bath sites is finite. While this can already be used to solve nonequilibrium cluster perturbation theory (NE-CPT) [2] for arbitrary long times, we improve upon NE-CPT by enforcing local continuity equations for density and energy to be respected. Total energy and particle number are then conserved during the time evolution.

[1] K. Balzer and M. Eckstein, Phys. Rev. B 89, 035148 (2014)

[2] M. Balzer and M. Potthoff, Phys. Rev. B 83, 195132 (2011)