Dresden 2020 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 47: Poster Session Correlated Electrons 2
TT 47.22: Poster
Wednesday, March 18, 2020, 15:00–19:00, P2/3OG
Energy Gap in Strongly Correlated Hubbard Clusters—Comparing Green Functions and DMRG — •Sönke Hese1, Jan-Philip Joost1, Niclas Schlünzen1, Claudio Verdozzi2, Peter Schmitteckert3, and Michael Bonitz1 — 1CAU Kiel, Germany — 2Lund University, Sweden — 3HQS Quantum Simulations, Germany
The (Fermi–)Hubbard model is a key system in the theory of strongly correlated electrons in solids. While the exact solution of the Hubbard Hamiltonian is known to possess a spin-symmetric ground state, in the mean-field approximation magnetic instabilities can, for on-site interactions beyond a critical Uc, induce the spontaneous breaking of spin symmetry leading to stable spin-density waves [1].
Using a Green function approach with higher order corrections to the self-energy, namely second Born and GW, we observe a similar effect at considerably larger interactions. Further, we find that similar inhomogeneous solutions are also present in spin-restricted calculations. By comparing to exact DMRG data for the 1D chain we find that these symmetry-broken states produce reliable data for the spectral function including the size of the Mott gap.
[1] J.-P. Joost, A.-P. Jauho, M. Bonitz, Nano Letters (2019), DOI:10.1021/acs.nanolett.9b04075