scholarly journals Theoretical Study of Unconventional Plasmon Generation by Solving Finite-Size 3D Hubbard Model within Mean Field Approximation

2019 ◽  
Vol 1354 ◽  
pp. 012017
Author(s):  
Dedi Prakasa ◽  
Muhammad Aziz Majidi
Keyword(s):  
Hubbard Model ◽  
Theoretical Study ◽  
Mean Field ◽  
Finite Size ◽  
Field Approximation ◽  
Mean Field Approximation

ANALYSIS OF THE TWO-DIMENSIONAL NEGATIVE-U HUBBARD MODEL BY COMPOSITE OPERATOR METHOD

1996 ◽  
Vol 10 (22) ◽  
pp. 2745-2756 ◽  
Author(s):  
T. DI MATTEO ◽  
F. MANCINI ◽  
S. MARRA ◽  
H. MATSUMOTO
Keyword(s):  
Hubbard Model ◽  
Chemical Potential ◽  
Particle Density ◽  
Mean Field ◽  
Finite Size ◽  
Operator Method ◽  
Field Approximation ◽  
Composite Operator ◽  
Mean Field Approximation ◽  
Two Dimensional

The two-dimensional negative-U Hubbard model is studied by means of the composite operator approach. In a generalized mean-field approximation we calculate different quantities, as the chemical potential, the double occupancy, the static uniform spin magnetic susceptibility and the density of states for various values of the particle density, attractive on-site interaction and temperature. Comparison with the results obtained by numerical analysis on finite size lattices shows a good agreement.

scholarly journals Энергетический спектр и оптические свойства фуллерена C-=SUB=-80-=/SUB=-(I-=SUB=-h-=/SUB=-) в модели Хаббарда

2021 ◽  
Vol 129 (10) ◽  
pp. 1227
Author(s):  
А.В. Силантьев
Keyword(s):  
Group Theory ◽  
Hubbard Model ◽  
Symmetry Group ◽  
Mean Field ◽  
Analytical Form ◽  
Field Approximation ◽  
Energy Spectra ◽  
Mean Field Approximation ◽  
The Mean

The anticommutative Green’s functions were derived in an analytical form, and the energy spectra of С80 fullerene and endohedral Y3N@C80 fullerene of symmetry group Ih were obtained within the Hubbard model in the mean-field approximation. Using group theory methods, the classification of energy states was carried out, and the allowed transitions in the energy spectra of С80 and Y3N@C80 molecules of symmetry group Ih were determined.

POSSIBLE COEXISTENCE OF ANTIFERROMAGNETISM AND SUPERCONDUCTIVITY IN THE HUBBARD MODEL

1988 ◽  
Vol 01 (09n10) ◽  
pp. 341-347 ◽  
Author(s):  
SHEN JUE-LIAN ◽  
SU ZHAO-BIN ◽  
DONG JIN-MING ◽  
YU LU
Keyword(s):  
Hubbard Model ◽  
High Temperature Superconductivity ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Antiferromagnetic Order ◽  
Effective Hamiltonian ◽  
Hamiltonian Approach ◽  
Theoretical Approaches ◽  
The Mean

The Hubbard model in the nearly half-filled case was studied in the mean field approximation using the effective Hamiltonian approach. Both antiferromagnetic order parameter and condensation of singlet pairs were considered. In certain parameter range the coexistence of antiferromagnetism and superconductivity is energetically favorable. Relations to the high temperature superconductivity and other theoretical approaches are also discussed.

scholarly journals Canted Spiral Magnetic Order in Layered Systems

2015 ◽  
Vol 233-234 ◽  
pp. 68-72
Author(s):  
Marat T. Timirgazin ◽  
Vitaly F. Gilmutdinov ◽  
Anatoly K. Arzhnikov
Keyword(s):  
Hubbard Model ◽  
Magnetic Structure ◽  
Magnetic Order ◽  
Magnetic State ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Layered Systems ◽  
Electron Hopping

Formation of a canted spiral magnetic order is studied in the framework of a mean-field approximation of the Hubbard model. It is revealed that this magnetic state can be stabilized under certain conditions in layered systemswith a relatively small interplane electron hopping. Example of an experimentally observed magnetic structure ofLa$_{2-x}$Sr$_x$CuO$_4$ is considered. It is shown that the canting magnetic order can be described in terms of a simplenon-relativistic band magnetism.

scholarly journals Testing the Monte Carlo–mean field approximation in the one-band Hubbard model

2014 ◽  
Vol 90 (20) ◽  
Author(s):  
Anamitra Mukherjee ◽  
Niravkumar D. Patel ◽  
Shuai Dong ◽  
Steve Johnston ◽  
Adriana Moreo ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Hubbard Model ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
The One

SPIN-CARRYING SLAVE BOSON REPRESENTATION FOR STRONGLY CORRELATED FERMION SYSTEMS

1989 ◽  
Vol 03 (12) ◽  
pp. 1833-1842
Author(s):  
P. Wölfle
Keyword(s):  
Hubbard Model ◽  
Anderson Model ◽  
Degrees Of Freedom ◽  
Mean Field ◽  
Field Approximation ◽  
Mean Field Approximation ◽  
Strongly Correlated ◽  
Dynamical Correlation ◽  
Fermion Systems ◽  
Boson Representation

We consider slave boson formulations of the Hubbard model, the t–J model and the Anderson model, in which spin and charge fermion degrees of freedom are represented by Bose fields. The approach has been applied to the Hubbard model generalizing the formulation of Kotliar and Ruckenstein. There the Gutzwiller solution is recovered as a saddle point. The method allows to find other types of mean field solutions in a systematic way. Dynamical correlation functions in mean field approximation as well as fluctuation contributions are also calculated.

scholarly journals High-Order Mean-Field Approximations for Adaptive Susceptible-Infected-Susceptible Model in Finite-Size Networks

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Kai Wang ◽  
Xiao Fan Liu ◽  
Dongchao Guo
Keyword(s):  
Exact Solutions ◽  
Computational Cost ◽  
Mean Field ◽  
Finite Size ◽  
Structural Evolution ◽  
Disease Outbreaks ◽  
Field Approximation ◽  
Epidemic Models ◽  
Mean Field Approximation ◽  
Complex Models

Exact solutions of epidemic models are critical for identifying the severity and mitigation possibility for epidemics. However, solving complex models can be difficult when interfering conditions from the real-world are incorporated into the models. In this paper, we focus on the generally unsolvable adaptive susceptible-infected-susceptible (ASIS) epidemic model, a typical example of a class of epidemic models that characterize the complex interplays between the virus spread and network structural evolution. We propose two methods based on mean-field approximation, i.e., the first-order mean-field approximation (FOMFA) and higher-order mean-field approximation (HOMFA), to derive the exact solutions to ASIS models. Both methods demonstrate the capability of accurately approximating the metastable-state statistics of the model, such as the infection fraction and network density, with low computational cost. These methods are potentially powerful tools in understanding, mitigating, and controlling disease outbreaks and infodemics.

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