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arXiv · 1808.07759

Solution of the "sign problem" for the half filled Hubbard-Holstein model

Seher Karakuzu·Kazuhiro Seki·Sandro Sorella
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Abstract

We show that, by an appropriate choice of auxiliary fields and exact integration of the phonon degrees of freedom, it is possible to define a 'sign-free' path integral for the so called Hubbard-Holstein model at half-filling. We use a statistical method, based on an accelerated and efficient Langevin dynamics, for evaluating all relevant correlation functions of the model. Preliminary calculations at $U/t=4$ and $U/t=1$, for $\omega_0/t=1$, indicate a quite extended region around $U \simeq {g^2 \over \omega_0}$ without either antiferromagnetic or charge-density-wave orders, separating two quantum critical points at zero temperature. The elimination of the sign problem in a model without explicit particle-hole symmetry may open new perspectives for strongly correlated models, even away from the purely attractive or particle-hole symmetric cases.

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Seher Karakuzu, Kazuhiro Seki, Sandro Sorella. 2018-08-23. Solution of the "sign problem" for the half filled Hubbard-Holstein model. https://doi.org/10.1103/physrevb.98.201108

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