Fluctuation diagnostics in the 2D Hubbard model from the dual-fermion method

Arzhang, Behnam (2019) Fluctuation diagnostics in the 2D Hubbard model from the dual-fermion method. Masters thesis, Memorial University of Newfoundland.

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In this thesis, we use the Dual Fermion approximation (DF) to study the Hubbard model on the 2D square lattice by using two-particle quantities such as susceptibilities and full vertex functions. In the first chapter we give an introduction to the strongly correlated systems including their definitions and features. Then, in the next chapter, to solve our model we present some numerical methods. The numerical methods that we used for our study are the dynamical mean-field theory (DMFT), the continuous-time auxiliary field impurity solver (CTAUX), Fluctuation diagnostics and Dual Fermion approximation (DF). The DF method provides high-resolution results for single-particle quantities such as the density of states (DOS) and Self Energy as well two particles spin susceptibility and vertex functions. With these results, we can present high-resolution results of the fluctuation diagnostics method with minimal computational expense. We examine the full Q-vector dependence of the extended self-energy at the Nodal and Antinodal k-points and provide interpretation for the claim that spin fluctuations are responsible for the observed metal-to-insulator behaviour.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/14314
Item ID: 14314
Additional Information: Includes bibliographical references (pages 61-67).
Keywords: Many Body systems, Hubbard model, strongly correlated systems, Fluctuation diagnostics, Dual Fermion approximation
Department(s): Science, Faculty of > Physics and Physical Oceanography
Date: November 2019
Date Type: Submission
Digital Object Identifier (DOI): https://doi.org/10.48336/hr41-1s39
Library of Congress Subject Heading: Solid state physics; Hubbard model.

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