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TT: Fachverband Tiefe Temperaturen
TT 23: Correlated Electrons – Poster I
TT 23.20: Poster
Montag, 9. März 2026, 18:00–20:00, P1
A Local-Wave Basis for the Hubbard Model — •Leon Wastl1,2 and Werner Dobrautz1,2,3,4 — 1Center for Advanced Systems Understanding, 02826 Görlitz, Germany — 2Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany — 3Center for Scalable Data Analytics and Artificial Intelligence Dresden/Leipzig, 01069 Dresden, Germany — 4Technical University Dresden, 01069 Dresden, Germany
The Fermi-Hubbard model is the prototypical model for interacting electrons and can be employed to describe a wide variety of physical phenomena. Its 2D version is believed to contain the fundamental physics describing low-temperature superconductivity. We present a new basis for the two-dimensional Hubbard model which we call the local-wave basis as it is a hybrid between real space and momentum space. We numerically study the advantages of our newly found transformation using the density matrix renormalization group (DMRG). Since DMRG in its more recent form is a method that is inherently one-dimensional as it is built on top of the matrix product state (MPS) formalism, we combine our local-wave basis with a new way of ordering the sites in the MPS based on a modified version of simulated annealing (SA) using the two-site mutual information as its objective function. Combined with this approach to find the optimal ordering, we show that our method yields lower energies for the same maximal bond dimension than both the pure momentum space and the real space formulation in the low to intermediate U/t regime.
Keywords: Hubbard Model; DMRG