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We introduce regular series expansion for weakly- and moderately-correlated fermionic systems, based on Fluctuating Local Field approach. The method relies on the explicit account of leading fluctuating mode(s) and is therefore suitable for…

Strongly Correlated Electrons · Physics 2024-12-25 Ya. S. Lyakhova , S. D. Semenov , A. I. Lichtenstein , A. N. Rubtsov

The phase diagram of the attractive Hubbard model with spatially inhomogeneous interactions is obtained using a single site dynamical mean field theory like approach. The model is characterized by three parameters: the interaction strength,…

Superconductivity · Physics 2009-11-13 Vijay B. Shenoy

Various auxiliary-particle approaches to treat electron correlations in many-electron models are analyzed. Applications to copper-oxide layered systems are discussed. The ground-state magnetic phase diagrams are considered within the…

Strongly Correlated Electrons · Physics 2019-02-21 V. Yu. Irkhin , P. A. Igoshev

The Hubbard model is the simplest model of interacting fermions on a lattice and is of similar importance to correlated electron physics as the Ising model is to statistical mechanics or the fruit fly to biomedical science. Despite its…

Strongly Correlated Electrons · Physics 2022-07-18 Mingpu Qin , Thomas Schäfer , Sabine Andergassen , Philippe Corboz , Emanuel Gull

Optical lattice experiments with ultracold fermion atoms and quantum gas microscopy have recently realized direct measurements of magnetic correlations at the site-resolved level. We calculate the short-range spin correlation functions in…

Strongly Correlated Electrons · Physics 2017-08-28 Mingpu Qin , Hao Shi , Shiwei Zhang

We report on the result of quantum Monte Carlo simulation of quasi-one-dimensional electron systems at 1/4-filling, considering organic superconductors such as TMTSF- and TMTTF-salts. We focus on the effect of dimensionality (interchain…

Strongly Correlated Electrons · Physics 2009-11-13 Tohru Aonuma , Yuki Fuseya , Masao Ogata

We show that the macroscopic magnetic and electronic properties of strongly correlated electron systems can be manipulated by coupling them to a cavity mode. As a paradigmatic example we consider the Fermi-Hubbard model and find that the…

Strongly Correlated Electrons · Physics 2019-03-29 Martin Kiffner , Jonathan Coulthard , Frank Schlawin , Arzhang Ardavan , Dieter Jaksch

Auxiliary field quantum Monte Carlo methods for Hubbard models are generally based on a Hubbard-Stratonovitch transformation where the field couples to the z-component of the spin. This transformation breaks SU(2) spin invariance. The…

Strongly Correlated Electrons · Physics 2007-05-23 F. F. Assaad

Systems with strong electronic Coulomb correlations often display rich phase diagrams exhibiting different ordered phases involving spin, charge, or orbital degrees of freedom. The theoretical description of the interplay of the…

Strongly Correlated Electrons · Physics 2024-01-09 E. Linnér , A. I. Lichtenstein , S. Biermann , E. A. Stepanov

We introduce a method that combines the power of both the lattice Green function Monte Carlo (LGFMC) with the auxiliary field techniques (AFQMC), and allows us to compute exact ground state properties of the Hubbard model for U<~ 4t on…

Strongly Correlated Electrons · Physics 2015-06-03 Sandro Sorella

An extensive Quantum Monte Carlo calculation is performed for the two-leg Hubbard ladder model to clarify whether the singlet pairing correlation decays slowly, which is predicted from the weak-coupling theory but controversial from…

Strongly Correlated Electrons · Physics 2009-10-28 Kazuhiko Kuroki , Takashi Kimura , Hideo Aoki

Auxiliary-field quantum Monte Carlo methods enable the calculation of thermal and ground state properties of correlated quantum many-body systems in model spaces that are many orders of magnitude larger than those that can be treated by…

Nuclear Theory · Physics 2019-07-29 Y. Alhassid

We propose theoretically that a magnetic field can realize spin-triplet superconductivity in repulsively interacting electron systems having strong ferromagnetic spin fluctuations. We confirm the general idea for the low-density Hubbard…

Strongly Correlated Electrons · Physics 2007-05-23 Ryotaro Arita , Kazuhiko Kuroki , Hideo Aoki

We discuss the impact of various improvements on simulations of dynamical overlap fermions using the Hybrid Monte Carlo algorithm. We focus on the usage of fat links and multiple pseudo-fermion fields.

High Energy Physics - Lattice · Physics 2011-07-18 Thomas DeGrand , Stefan Schaefer

We tutorially review the determinantal Quantum Monte Carlo method for fermionic systems, using the Hubbard model as a case study. Starting with the basic ingredients of Monte Carlo simulations for classical systems, we introduce aspects…

Strongly Correlated Electrons · Physics 2007-05-23 Raimundo R. dos Santos

Ground state properties of the Hubbard model on a two-dimensional square lattice are studied by the auxiliary-field quantum Monte Carlo method. Accurate results for energy, double occupancy, effective hopping, magnetization, and momentum…

Strongly Correlated Electrons · Physics 2016-08-10 Mingpu Qin , Hao Shi , Shiwei Zhang

The dual-fermion approach provides a formally exact prescription for calculating properties of a correlated electron system in terms of a diagrammatic expansion around dynamical mean-field theory (DMFT). Most practical implementations,…

Strongly Correlated Electrons · Physics 2017-08-02 Jan Gukelberger , Evgeny Kozik , Hartmut Hafermann

We demonstrate that the inclusion of a BCS importance function dramatically increases the efficiency of the auxiliary field method for strong pairing. We calculate the ground-state energy of an unpolarized fermi gas at unitarity with up to…

Quantum Gases · Physics 2011-12-12 J. Carlson , Stefano Gandolfi , Kevin E. Schmidt , Shiwei Zhang

Building on recent solutions of the fermion sign problem for specific models we present two continuous-time quantum Monte Carlo methods for efficient simulation of mass-imbalanced Hubbard models on bipartite lattices at half-filling. For…

Strongly Correlated Electrons · Physics 2015-12-18 Ye-Hua Liu , Lei Wang

Dynamic cluster Monte Carlo calculations for the doped two-dimensional Hubbard model are used to study the irreducible particle-particle vertex responsible for $d_{x^2-y^2}$ pairing in this model. This vertex increases with increasing…

Superconductivity · Physics 2009-11-11 T. A. Maier , M. S. Jarrell , D. J. Scalapino