Strongly Correlated Multi Orbital Systems

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Strongly Correlated Multi Orbital Systems

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Author : Nicolaus Parragh
language : de
Publisher:
Release Date : 2013

Strongly Correlated Multi Orbital Systems written by Nicolaus Parragh and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.

Emergent Low Temperature Phases In Strongly Correlated Multi Orbital And Cold Atom Systems

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Author : Christoph Minol Puetter
language : en
Publisher:
Release Date : 2012

Emergent Low Temperature Phases In Strongly Correlated Multi Orbital And Cold Atom Systems written by Christoph Minol Puetter and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.

Dynamical Mean Field Theory For Strongly Correlated Materials

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Author : Volodymyr Turkowski
language : en
Publisher: Springer Nature
Release Date : 2021-04-22

Dynamical Mean Field Theory For Strongly Correlated Materials written by Volodymyr Turkowski and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-04-22 with Technology & Engineering categories.

​​This is the first book that provides a detailed summary of one of the most successful new condensed matter theories - dynamical mean-field theory (DMFT) - in both static and dynamical cases of systems of different sizes. DMFT is one of the most successful approaches to describe the physical properties of systems with strong electron-electron correlations such as bulk materials, multi-layers, surfaces, 2D materials and nanostructures in both metallic and insulating phases. Strongly correlated materials usually include partially-filled localized d- or f-orbitals, and DMFT takes into account crucial for these systems time-resolved interaction between electrons when they “meet” on one atom and occupy one of these orbitals. The First Part of the book covers the general formalism of DMFT as a many-body theory, followed by generalizations of the approach on the cases of finite systems and out-of-equilibrium regime. In the last Chapter of the First Part we discuss generalizations of the approach on the case when the non-local interactions are taken into account. The Second Part of the book covers methodologies of merging DMFT with ab initio static Density Functional Theory (DFT) and Time-Dependent DFT (TDDFT) approaches. Such combined DFT+DMFT and DMFT+TDDFT computational techniques allow one to include the effects of strong electron-electron correlations at the accurate ab initio level. These tools can be applied to complex multi-atom multi-orbital systems currently not accessible to DMFT. The book helps broad audiences of students and researchers from the theoretical and computational communities of condensed matter physics, material science, and chemistry to become familiar with this state-of-art approach and to use it for reaching a deeper understanding of the properties of strongly correlated systems and for synthesis of new technologically-important materials.

Numerical And Analytical Approaches To Strongly Correlated Electron Systems

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Author :
language : en
Publisher:
Release Date : 2006

Numerical And Analytical Approaches To Strongly Correlated Electron Systems written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.

In this thesis we consider three different models for strongly correlated electrons, namely a multi-band Hubbard model as well as the spinless Falicov-Kimball model, both with a semi-elliptical density of states in the limit of infinite dimensions d, and the attractive Hubbard model on a square lattice in d=2. In the first part, we study a two-band Hubbard model with unequal bandwidths and anisotropic Hund's rule coupling (J_z-model) in the limit of infinite dimensions within the dynamical mean-field theory (DMFT). Here, the DMFT impurity problem is solved with the use of quantum Monte Carlo (QMC) simulations. Our main result is that the J_z-model describes the occurrence of an orbital-selective Mott transition (OSMT), in contrast to earlier findings. We investigate the model with a high-precision DMFT algorithm, which was developed as part of this thesis and which supplements QMC with a high-frequency expansion of the self-energy. The main advantage of this scheme is the extraordinary accuracy of the numerical solutions, which can be obtained already with moderate computational effort, so that studies of multi-orbital systems within the DMFT+QMC are strongly improved. We also found that a suitably defined Falicov-Kimball (FK) model exhibits an OSMT, revealing the close connection of the Falicov-Kimball physics to the J_z-model in the OSM phase. In the second part of this thesis we study the attractive Hubbard model in two spatial dimensions within second-order self-consistent perturbation theory. This model is considered on a square lattice at finite doping and at low temperatures. Our main result is that the predictions of first-order perturbation theory (Hartree-Fock approximation) are renormalized by a factor of the order of unity even at arbitrarily weak interaction (U->0). The renormalization factor q can be evaluated as a function of the filling n for 0n

First Principles Simulations Of Multi Orbital Systems With Strong Electronic Correlations

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Author : Brigitte Surer
language : en
Publisher:
Release Date : 2011

First Principles Simulations Of Multi Orbital Systems With Strong Electronic Correlations written by Brigitte Surer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.

Strongly Correlated Systems

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Author : Adolfo Avella
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-04-05

Strongly Correlated Systems written by Adolfo Avella and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-04-05 with Science categories.

This volume presents, for the very first time, an exhaustive collection of those modern numerical methods specifically tailored for the analysis of Strongly Correlated Systems. Many novel materials, with functional properties emerging from macroscopic quantum behaviors at the frontier of modern research in physics, chemistry and material science, belong to this class of systems. Any technique is presented in great detail by its own inventor or by one of the world-wide recognized main contributors. The exposition has a clear pedagogical cut and fully reports on the most relevant case study where the specific technique showed to be very successful in describing and enlightening the puzzling physics of a particular strongly correlated system. The book is intended for advanced graduate students and post-docs in the field as textbook and/or main reference, but also for other researchers in the field who appreciate consulting a single, but comprehensive, source or wishes to get acquainted, in a as painless as possible way, with the working details of a specific technique.

Non Equilibrium Processes In Strongly Correlated Electron Systems With Multiple Orbital Degrees Of Freedom

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Author :
language : en
Publisher:
Release Date : 2016

Non Equilibrium Processes In Strongly Correlated Electron Systems With Multiple Orbital Degrees Of Freedom written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.

Multi Species Systems In Optical Lattices

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Author : Fernanda Pinheiro
language : en
Publisher: Springer
Release Date : 2016-08-12

Multi Species Systems In Optical Lattices written by Fernanda Pinheiro and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-08-12 with Science categories.

This highly interdisciplinary thesis covers a wide range of topics relating to the interface of cold atoms, quantum simulation, quantum magnetism and disorder. With a self-contained presentation, it provides a broad overview of the rapidly evolving area of cold atoms and is of interest to both undergraduates and researchers working in the field. Starting with a general introduction to the physics of cold atoms and optical lattices, it extends the theory to that of systems with different multispecies atoms. It advances the theory of many-body quantum systems in excited bands (of optical lattices) through an extensive study of the properties of both the mean-field and strongly correlated regimes. Particular emphasis is given to the context of quantum simulation, where as shown here, the orbital degree of freedom in excited bands allows the study of exotic models of magnetism not easily achievable with the previous alternative systems. In addition, it proposes a new model Hamiltonian that serves as a quantum simulator of various disordered systems in different symmetry classes that can easily be reproduced experimentally. This is of great interest, especially for the study of disorder in 2D quantum systems.

Orbital Selectivity In Strongly Correlated Fermionic Systems From Materials To Cold Atoms

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Author : Emilio Winograd
language : en
Publisher:
Release Date : 2013

Orbital Selectivity In Strongly Correlated Fermionic Systems From Materials To Cold Atoms written by Emilio Winograd and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.

This thesis focuses on multiorbital aspects of strongly correlated fermionic systems. In particular, it focuses on the existence of orbital differentiation in which coexistence of itinerant and localized character can be associated to different orbitals. This subject is discussed in the context of cold atoms and materials, providing a bridge between both communities.In the first part of the thesis, we give an insight into the problem of strong correlations in materials, and we introduce the concept of 'orbital-selective Mott transition'. We also provide the main tools to understand how materials can be simulated with cold atoms experiments, and we present important related results in the context of the metal-Mott insulator transition. The technical aspects, based on dynamical mean-field theory are also discussed, and the solution of two key models of strongly correlated fermionic systems, i.e., the Hubbard model (HM) and the Falicov-Kimball model (FKM), are reviewed.Then we study in detail the physics of two interacting fermionic species with different masses in an optical lattice. We establish the different phases (with and without long-range order) in terms of the interactions strength (U), mass ratio and temperature (T), and also discuss the thermodynamic variables, which are relevant in cold atoms experiments. We show that in the metallic phase (U below a critical value) and for some degree of mass imbalance, a crossover appears between a Fermi-liquid metallic state at low T, and an 'orbital-selective' state at higher T, where the heavy fermions effectively localize while the light species remain itinerant. Hence, we propose this minimal model for addressing orbital-selective physics with cold atoms experiments.Based on the properties of the studied model, we propose the 'entropic chromatography' as a new method for cooling fermionic atoms in optical lattices. We discuss its efficiency and limitations, and provide some ideas in order to overcome them.In the last part of the thesis we generalize the previous model to a model relevant for multiband correlated materials that can display orbital differentiation. We show that the orbital-selective Mott state can be stable under lattice distortions modeled by local hybridization between the orbitals. However, the Mott state is characterized by a pseudogap, where charge fluctuations abruptly reduce, but the state remains compressible. In connection with the previous model, we discuss the temperature-induced orbital-selective crossover in this problem, we compare our results with photoemission experiments, and predict what would happen in materials that display local hybridization between the bands.

Hubbard Operators In The Theory Of Strongly Correlated Electrons

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Author : S. G. Ovchinnikov
language : en
Publisher: Imperial College Press
Release Date : 2004

Hubbard Operators In The Theory Of Strongly Correlated Electrons written by S. G. Ovchinnikov and has been published by Imperial College Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with Science categories.

This book provides the first systematic discourse on a very peculiarapproach to the theory of strongly correlated systems. HubbardX-operators have been known for a long time but have not been widelyused because of their awkward algebra. The book shows that it ispossible to deal with X-operators even in the general multilevel localeigenstate system, and not just in the case of the nondegenerateHubbard model. X-operators provide the natural language for describingquasiparticles in the Hubbard subbands with unusual doping andtemperature-dependent band structures.