On the paper ?single-particle Green's function in the anisotropic heisenberg model II. Allowance for higher correlation functions?

1976 ◽  
Vol 27 (2) ◽  
pp. 484-484 ◽  
Author(s):  
Yu. G. Rudoi ◽  
Yu. A. Tserkovnikov
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Single Particle ◽  
Correlation Functions ◽  
Heisenberg Model ◽  
Anisotropic Heisenberg Model

THE FERMIONIC GREEN'S FUNCTION THEORY FOR CALCULATION OF MAGNETIZATION

2002 ◽  
Vol 16 (25) ◽  
pp. 3803-3816 ◽  
Author(s):  
HUAI-YU WANG ◽  
KE-QIU CHEN ◽  
EN-GE WANG
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Heisenberg Model ◽  
Function Theory ◽  
Present Theory ◽  
Higher Order ◽  
Statistical Average ◽  
Universal Formula ◽  
Anisotropic Heisenberg Model ◽  
Three Components

The fermionic Green's function theory of Heisenberg-like Hamiltonian is presented in this paper. For the case that the Hamiltonian is isotropic and the higher-order Green's function is asymmetrically decoupled, the present theory is equivalent to the bosonic Green's function theory. When the Hamiltonian is anisotropic and the higher-order Green's function is symmetrically decoupled, it gives the universal formula to calculate the three components of statistical average of spin operators which one encountered when dealing with ferromagnetic or ferroelectric systems described by anisotropic Heisenberg model or pseudospin model respectively. Both cases of <Sz> ≠ 0 and <Sz> = 0 are investigated. Explicit expressions are derived for spin value S = 1/2, 1, 3/2, 2, and 5/2. General expressions for any S value are suggested.

scholarly journals The Use of Parameter-Free Correlation Functions in Green's Function Monte Carlo Simulations of Small Electronic Systems

1997 ◽  
Vol 52 (11) ◽  
pp. 793-802 ◽  
Author(s):  
C. Mecke ◽  
F. F. Seelig
Keyword(s):  
Monte Carlo ◽  
Green’S Function ◽  
Green's Function ◽  
Correlation Functions ◽  
High Performance ◽  
Limited Range ◽  
Electronic Energy ◽  
Simple Expression ◽  
Electronic Systems ◽  
Green's Function Monte Carlo

Abstract Using an old formulation for correlation functions with correct cusp-behaviour, the Schrödinger equation transforms to a new differential equation which provides a very simple expression for the local electronic energy with limited range. This, together with the simplicity of the formulation promises a high performance in Green's function Monte Carlo (GFMC) simulations of small electronic systems. The behaviour of the local energy is studied on a few simple examples because the variance of this function determines the quality of the results in the GFMC methods. Calculations for one-and two-electron systems are presented and compared with results from well-known functions. The form of the function is then extended to systems with more than two electrons. Results for the Be atom are given and the extension to larger electronic systems is discussed.

scholarly journals Elementary band representations for the single-particle Green's function of interacting topological insulators

2021 ◽  
Vol 104 (8) ◽  
Author(s):  
Dominik Lessnich ◽  
Stephen M. Winter ◽  
Mikel Iraola ◽  
Maia G. Vergniory ◽  
Roser Valentí
Keyword(s):  
Green’S Function ◽  
Green's Function ◽  
Single Particle ◽  
Topological Insulators ◽  
Elementary Band
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