scholarly journals Equation-of-motion series expansion of double-time Green's functions

2015 ◽  
Vol 92 (16) ◽  
Author(s):  
Ning-Hua Tong
Keyword(s):  
Series Expansion ◽  
Green's Functions ◽  
Green’S Functions ◽  
Equation Of Motion ◽  
Double Time

SOME REMARKS ON THE EQUATION OF MOTION METHOD FOR THE GREEN’S FUNCTION CALCULATIONS

1991 ◽  
Vol 05 (15) ◽  
pp. 2515-2529
Author(s):  
R. TARANKO
Keyword(s):  
Green's Function ◽  
Projection Operator ◽  
Continued Fractions ◽  
Green's Functions ◽  
Green’S Functions ◽  
Equation Of Motion ◽  
Operator Technique ◽  
Projection Operator Technique ◽  
Double Time ◽  
Motion Method

The retarded, double-time Green’s Functions are studied using different modifications of the projection operator technique. It is shown that the results of all these approaches can be written in the form of the finite or infinite continued fractions. Moreover, they lead to the same expansions for the Green’s Functions when terminated at the same level.

Nonequilibrium Green’s Functions

2018 ◽  
Author(s):  
Klaus Morawetz
Keyword(s):  
Green’S Function ◽  
Quantum Transport ◽  
Green's Function ◽  
Green's Functions ◽  
Green’S Functions ◽  
Equation Of Motion ◽  
Diagrammatic Technique ◽  
Initial Correlations ◽  
Nonequilibrium Green’S Functions ◽  
Nonequilibrium Green's Functions

The method of the equation of motion is used to derive the Martin–Schwinger hierarchy for the nonequilibrium Green’s functions. The formal closure of the hierarchy is reached by using the selfenergy which provides a recipe for how to construct selfenergies from approximations of the two-particle Green’s function. The Langreth–Wilkins rules for a diagrammatic technique are shown to be equivalent to the weakening of initial correlations. The quantum transport equations are derived in the general form of Kadanoff and Baym equations. The information contained in the Green’s function is discussed. In equilibrium this leads to the Matsubara diagrammatic technique.

MODIFIED HUBBARD DECOUPLING FOR THE EMERY MODEL

1995 ◽  
Vol 09 (25) ◽  
pp. 1635-1641
Author(s):  
LEW GEHLHOFF
Keyword(s):  
Single Particle ◽  
Green's Functions ◽  
Green’S Functions ◽  
Equation Of Motion ◽  
Higher Order ◽  
Exact Results ◽  
Emery Model ◽  
Spin Degeneracy ◽  
Motion Method ◽  
Large Spin

We consider a version of the Emery model with large spin degeneracy N and use the X-operator formulation and the equation-of-motion method to determine the single-particle Green’s functions. We propose a modified Hubbard decoupling technique for the higher-order Green’s functions appearing in this equation of motion. By applying it to the above model in the limit N→∞ we obtain the exact results.

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