Projective Truncation Approximation for Equations of Motion of Two-Time Green's Functions

Abstract

In the equation of motion approach to the two-time Green's functions, conventional Tyablikov-type truncation of the chain of equations is rather arbitrary and apt to violate the analytical structure of Green's functions. Here, we propose a practical way to truncate the equations of motion using operator projection. The partial projection approximation is introduced to evaluate the Liouville matrix. It guarantees the causality of Green's functions, fulfills the time translation invariance and the particle-hole symmetry, and is easy to implement in a computer. To benchmark this method, we study the Anderson impurity model using the operator basis at the level of Lacroix approximation. Improvement over conventional Lacroix approximation is observed. The distribution of Kondo screening in the energy space is studied using this method.

arXiv comment14 pages, 8 figures, published version

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• Natural Orbital-Based Lanczos Method for Anderson Impurity Models
• Projective-truncation-approximation study of the one-dimensional ${\varphi }^4$ lattice model
• Spatial spin-spin correlations of the single-impurity Anderson model with a ferromagnetic bath
• Equation of motion truncation scheme based on partial orthogonalization
• Improved strong-coupling perturbation theory of the symmetric Anderson impurity model
• An improved particle swarm optimization algorithm and its application to search for new magnetic ground states in the Hubbard model
• On non-canonical degrees of freedom
• Probing quasiparticle excitations in a doped Mott insulator via Friedel oscillations
• Self-Consistent Random Phase Approximation from Projective Truncation Approximation Formalism