scholarly journals Chemical potential and the self-energy correction of spinors: Further results on the large-U hubbard model

1991 ◽  
Vol 14 (4) ◽  
pp. 1049-1052
Author(s):  
L Hu ◽  
K W Yu
Keyword(s):  
Hubbard Model ◽  
Chemical Potential ◽  
The Self ◽  
Energy Correction ◽  
Self Energy

scholarly journals Self-Consistent Calculation of Particle-Hole Diagrams on the Matsubara Frequency: Flex Approximation

1997 ◽  
Vol 08 (05) ◽  
pp. 1145-1158
Author(s):  
J. J. Rodríguez-Núñez ◽  
S. Schafroth
Keyword(s):  
Hubbard Model ◽  
Imaginary Part ◽  
Chemical Potential ◽  
Order Approximation ◽  
The Self ◽  
Green Functions ◽  
Matsubara Frequency ◽  
Self Energy ◽  
Peak Structure ◽  
Self Consistent

We implement the numerical method of summing Green function diagrams on the Matsubara frequency axis for the fluctuation exchange (FLEX) approximation. Our method has previously been applied to the attractive Hubbard model for low density. Here we apply our numerical algorithm to the Hubbard model close to half filling (ρ =0.40), and for T/t = 0.03, in order to study the dynamics of one- and two-particle Green functions. For the values of the chosen parameters we see the formation of three branches which we associate with the two-peak structure in the imaginary part of the self-energy. From the imaginary part of the self-energy we conclude that our system is a Fermi liquid (for the temperature investigated here), since Im Σ( k , ω) ≈ w2 around the chemical potential. We have compared our fully self-consistent FLEX solutions with a lower order approximation where the internal Green functions are approximated by free Green functions. These two approches, i.e., the fully self-consistent and the non-self-consistent ones give different results for the parameters considered here. However, they have similar global results for small densities.

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 NONEQUILIBRIUM THERMO FIELD DYNAMICS FOR RELATIVISTIC COMPLEX SCALAR AND DIRAC FIELDS

2012 ◽  
Vol 27 (14) ◽  
pp. 1250078 ◽  
Author(s):  
YUICHI MIZUTANI ◽  
TOMOHIRO INAGAKI
Keyword(s):  
Chemical Potential ◽  
Relativistic Quantum ◽  
The Self ◽  
Quantum Field Theories ◽  
Renormalization Condition ◽  
Complex Scalar ◽  
Dirac Fields ◽  
Self Energy ◽  
Thermo Field Dynamics ◽  
Self Consistency

Relativistic quantum field theories for complex scalar and Dirac fields are investigated in nonequilibrium thermo field dynamics. The thermal vacuum is defined by the Bogoliubov transformed creation and annihilation operators. Two independent Bogoliubov parameters are introduced for a charged field. Its difference naturally induces the chemical potential. Time-dependent thermal Bogoliubov transformation generates the thermal counterterms. We fix the terms by the self-consistency renormalization condition. Evaluating the thermal self-energy under the self-consistency renormalization condition, we derive the quantum Boltzmann equations for the relativistic fields.

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 ON THE NONRELATIVISTIC LIMIT OF THE φ4 THEORY IN 2+1 DIMENSIONS

1996 ◽  
Vol 11 (36) ◽  
pp. 2825-2836 ◽  
Author(s):  
M. GOMES ◽  
J.M.C. MALBOUISSON ◽  
A.J. DA SILVA
Keyword(s):  
Quantum Theory ◽  
Scalar Field ◽  
Scattering Amplitude ◽  
Nonrelativistic Limit ◽  
Low Energy ◽  
The Self ◽  
Energy Correction ◽  
Real Scalar ◽  
Self Energy

We study the nonrelativistic limit of the quantum theory of a real scalar field with quartic self-interaction. The two-body scattering amplitude is written in such way as to separate the contributions of high and low energy intermediary states. From this result and the two-loop computation of the self-energy correction, we determine an effective nonrelativistic action.

Level dependence of the self-energy correction to the Hartree-Fock single-particle energies in 208Pb

1984 ◽  
Vol 140 (3-4) ◽  
pp. 163-166 ◽  
Author(s):  
P.F. Bortignon ◽  
R.A. Broglia ◽  
C.H. Dasso ◽  
C. Mahaux
Keyword(s):  
Single Particle ◽  
The Self ◽  
Energy Correction ◽  
Hartree Fock ◽  
Self Energy
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