Second order self-energy of the two-dimensional Hubbard model

1997 ◽  
Vol 103 (1) ◽  
pp. 41-44 ◽  
Author(s):  
Stéphane Daul ◽  
Michael Dzierzawa
Keyword(s):  
Hubbard Model ◽  
Second Order ◽  
Two Dimensional ◽  
Self Energy

ANISOTROPIC PSEUDOGAP IN THE HALF-FILLING TWO-DIMENSIONAL HUBBARD MODEL AT FINITE TEMPERATURE

2000 ◽  
Vol 14 (21) ◽  
pp. 2271-2286
Author(s):  
TAIICHIRO SAIKAWA ◽  
ALVARO FERRAZ
Keyword(s):  
Fermi Surface ◽  
Fermi Level ◽  
Hubbard Model ◽  
Spectral Function ◽  
Density Of States ◽  
Spin Fluctuation ◽  
The Self ◽  
Two Dimensional ◽  
Self Energy ◽  
Half Filling

We have studied the pseudogap formation in the single-particle spectra of the half-filling two-dimensional Hubbard model. Using a Green's function with the one-loop self-energy correction of the spin and charge fluctuations, we have numerically calculated the self-energy, the spectral function, and the density of states in the weak-coupling regime at finite temperatures. Pseudogap formations have been observed in both the density of states and the spectral function at the Fermi level. The pseudogap in the spectral function is explained by the non-Fermi-liquid-like nature of the self-energy. The anomalous behavior in the self-energy is caused by both the strong antiferromagnetic spin fluctuation and the nesting condition on the non-interacting Fermi surface. In the present approximation, we find a logarithmic singularity in the integrand of the self-energy imaginary part. The pseudogap in the spectral function is highly momentum dependent on the Fermi surface. This anisotropy of the pseudogap is produced by the flatness of the band dispersion around the saddle point rather than the nesting condition on the Fermi level.

scholarly journals Momentum structure of the self-energy and its parametrization for the two-dimensional Hubbard model

2016 ◽  
Vol 93 (19) ◽  
Author(s):  
P. Pudleiner ◽  
T. Schäfer ◽  
D. Rost ◽  
G. Li ◽  
K. Held ◽  
...  
Keyword(s):  
Hubbard Model ◽  
The Self ◽  
Two Dimensional ◽  
Self Energy

scholarly journals Second-order dual fermion approach to the Mott transition in the two-dimensional Hubbard model

2018 ◽  
Vol 98 (15) ◽  
Author(s):  
Erik G. C. P. van Loon ◽  
Mikhail I. Katsnelson ◽  
Hartmut Hafermann
Keyword(s):  
Hubbard Model ◽  
Mott Transition ◽  
Second Order ◽  
Two Dimensional

scholarly journals Quasi-particle functional Renormalisation Group calculations in the two-dimensional half-filled Hubbard model at finite temperatures

2020 ◽  
Vol 9 (6) ◽  
Author(s):  
Daniel Rohe ◽  
Carsten Honerkamp
Keyword(s):  
Hubbard Model ◽  
Fermi Liquid ◽  
Renormalisation Group ◽  
Direct Access ◽  
Two Dimensional ◽  
Quasi Particle ◽  
Energy Data ◽  
Self Energy ◽  
Real Frequency

We present a highly parallelisable scheme for treating functional Renormalisation Group equations which incorporates a quasi-particle-based feedback on the flow and provides direct access to real-frequency self-energy data. This allows to map out the boundaries of Fermi-liquid regimes and to study the effect of quasi-particle degradation near Fermi liquid instabilities. As a first application, selected results for the two-dimensional half-filled perfectly nested Hubbard model are shown.

scholarly journals Multiloop functional renormalization group for the two-dimensional Hubbard model: Loop convergence of the response functions

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Agnese Tagliavini ◽  
Cornelia Hille ◽  
Fabian Kugler ◽  
Sabine Andergassen ◽  
Alessandro Toschi ◽  
...  
Keyword(s):  
Renormalization Group ◽  
Hubbard Model ◽  
Two Dimensional ◽  
Response Functions ◽  
Functional Renormalization Group ◽  
Self Energy ◽  
Numerical Effort ◽  
Physical Response ◽  
The Common ◽  
Made In

We present a functional renormalization group (fRG) study of the two dimensional Hubbard model, performed with an algorithmic implementation which lifts some of the common approximations made in fRG calculations. In particular, in our fRG flow; (i) we take explicitly into account the momentum and the frequency dependence of the vertex functions; (ii) we include the feedback effect of the self-energy; (iii) we implement the recently introduced multiloop extension which allows us to sum up all the diagrams of the parquet approximation with their exact weight. Due to its iterative structure based on successive one-loop computations, the loop convergence of the fRG results can be obtained with an affordable numerical effort. In particular, focusing on the analysis of the physical response functions, we show that the results become independent from the chosen cutoff scheme and from the way the fRG susceptibilities are computed, i.e., either through flowing couplings to external fields, or through a “post-processing” contraction of the interaction vertex at the end of the flow. The presented substantial refinement of fRG-based computation schemes paves a promising route towards future quantitative fRG analyses of more challenging systems and/or parameter regimes.

scholarly journals The second-order reduced density matrix method and the two-dimensional Hubbard model

2013 ◽  
Vol 1003 ◽  
pp. 22-27 ◽  
Author(s):  
James S.M. Anderson ◽  
Maho Nakata ◽  
Ryo Igarashi ◽  
Katsuki Fujisawa ◽  
Makoto Yamashita
Keyword(s):  
Density Matrix ◽  
Hubbard Model ◽  
Matrix Method ◽  
Second Order ◽  
Reduced Density Matrix ◽  
Two Dimensional ◽  
Reduced Density
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