Regensburg 2019 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 17: Poster Session: Correlated Electrons 1

TT 17.38: Poster

Monday, April 1, 2019, 15:00–18:30, Poster D

Nonequilibrium Green Functions for Excited Lattice Systems—A Case Study of the Artificial Damping — •Niclas Schlünzen, Jan-Philip Joost, and Michael Bonitz — CAU Kiel, Germany

The accurate description of nonequilibrium dynamics in correlated quantum-many-body systems remains to be a driving force for current research in condensed-matter physics and beyond. Among others, the nonequilibrium Green functions (NEGF) method has proven to be a powerful tool to predict quantum behavior^[1], especially in the context of lattice systems^[2]. Due to its two-time structure the NEGF approach gives access to two-particle and two-time observables, e.g. the double occupation and spectral properties. In 2009, von Friesen et. al reported the occurance of unphysical damping effects in NEGF calculations for strongly excited Hubbard clusters^[3]. Since then, several ways have been proposed to overcome this deficiency by reducing the degree of selfconsistency^[3,4]. Here, we focus on (time-dependent) spectral properties for finite Hubbard systems and the respective impact of both the artificial damping itself and the common methods of resolution. Furthermore, we introduce a controlled way to adjust the depth of selfconsistency based on the Dyson equation and compare its performance to previous approaches.
K. Balzer and M. Bonitz, Lect. Notes Phys. 867 (2013)
N. Schlünzen et al., Phys. Rev. B 95, 165139 (2017)
M. P. von Friesen et al., Phys. Rev. Lett. 103 176404 (2009)
S. Hermanns et al., Phys. Rev. B 90, 125111 (2014)